Added BETA api for Tab Bar/Tabs widgets. (#261, #351) (merged this feature from the from Docking branch so it can be used earlier as as standalone feature)

- Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
- Added ImGuiTabBarFlags flags for BeginTabBar().
- Added ImGuiTabItemFlags flags for BeginTabItem().
- Style: Added ImGuiCol_Tab, ImGuiCol_TabHovered, ImGuiCol_TabActive, ImGuiCol_TabUnfocused, ImGuiCol_TabUnfocusedActive colors.
- Demo: Added Layout->Tabs demo code.
- Demo: Added "Documents" example app showcasing possible use for tabs.

docs/CHANGELOG.txt

@@ -39,6 +39,15 @@ Breaking Changes:
   The addition of new configuration options in the Docking branch is pushing for a little reorganization of those names.
 
 Other Changes:
+- Added BETA api for Tab Bar/Tabs widgets: (#261, #351)
+  - Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
+  - Added ImGuiTabBarFlags flags for BeginTabBar().
+  - Added ImGuiTabItemFlags flags for BeginTabItem().
+  - Style: Added ImGuiCol_Tab, ImGuiCol_TabHovered, ImGuiCol_TabActive, ImGuiCol_TabUnfocused, ImGuiCol_TabUnfocusedActive colors.
+  - Demo: Added Layout->Tabs demo code.
+  - Demo: Added "Documents" example app showcasing possible use for tabs.
+  This feature was merged from the Docking branch in order to allow the use of regular tabs in your code.
+  (It does not provide the docking/splitting/merging of windows available in the Docking branch)
 - Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering 
   the ID, as a convenience to avoid using the ### operator.
 - Resizing windows from edge is now enabled by default (io.ConfigWindowsResizeFromEdges=true). Note that 

docs/TODO.txt

@@ -127,7 +127,8 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - dock: docking extension
  - dock: dock out from a collapsing header? would work nicely but need emitting window to keep submitting the code.
 
- - tabs: re-ordering, close buttons, context menu, persistent order (#261, #351)
+ - tabs: make EndTabBar fail if users doesn't respect BeginTabBar return value, for consistency/future-proofing.
+ - tabs: persistent order/focus in BeginTabBar() api (#261, #351)
 
  - ext: stl-ish friendly extension (imgui_stl.h) that has wrapper for std::string, std::vector etc.
 

imgui.cpp

@@ -1015,6 +1015,8 @@ ImGuiStyle::ImGuiStyle()
     ScrollbarRounding       = 9.0f;             // Radius of grab corners rounding for scrollbar
     GrabMinSize             = 10.0f;            // Minimum width/height of a grab box for slider/scrollbar
     GrabRounding            = 0.0f;             // Radius of grabs corners rounding. Set to 0.0f to have rectangular slider grabs.
+    TabRounding             = 4.0f;             // Radius of upper corners of a tab. Set to 0.0f to have rectangular tabs.
+    TabBorderSize           = 0.0f;             // Thickness of border around tabs.
     ButtonTextAlign         = ImVec2(0.5f,0.5f);// Alignment of button text when button is larger than text.
     DisplayWindowPadding    = ImVec2(19,19);    // Window position are clamped to be visible within the display area by at least this amount. Only applies to regular windows.
     DisplaySafeAreaPadding  = ImVec2(3,3);      // If you cannot see the edge of your screen (e.g. on a TV) increase the safe area padding. Covers popups/tooltips as well regular windows.
@@ -1038,6 +1040,7 @@ void ImGuiStyle::ScaleAllSizes(float scale_factor)
     PopupRounding = ImFloor(PopupRounding * scale_factor);
     FramePadding = ImFloor(FramePadding * scale_factor);
     FrameRounding = ImFloor(FrameRounding * scale_factor);
+    TabRounding = ImFloor(TabRounding * scale_factor);
     ItemSpacing = ImFloor(ItemSpacing * scale_factor);
     ItemInnerSpacing = ImFloor(ItemInnerSpacing * scale_factor);
     TouchExtraPadding = ImFloor(TouchExtraPadding * scale_factor);
@@ -2160,17 +2163,8 @@ void ImGui::RenderTextWrapped(ImVec2 pos, const char* text, const char* text_end
 
 // Default clip_rect uses (pos_min,pos_max)
 // Handle clipping on CPU immediately (vs typically let the GPU clip the triangles that are overlapping the clipping rectangle edges)
-void ImGui::RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, const ImVec2& align, const ImRect* clip_rect)
+void ImGui::RenderTextClippedEx(ImDrawList* draw_list, const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_display_end, const ImVec2* text_size_if_known, const ImVec2& align, const ImRect* clip_rect)
 {
-    // Hide anything after a '##' string
-    const char* text_display_end = FindRenderedTextEnd(text, text_end);
-    const int text_len = (int)(text_display_end - text);
-    if (text_len == 0)
-        return;
-
-    ImGuiContext& g = *GImGui;
-    ImGuiWindow* window = g.CurrentWindow;
-
     // Perform CPU side clipping for single clipped element to avoid using scissor state
     ImVec2 pos = pos_min;
     const ImVec2 text_size = text_size_if_known ? *text_size_if_known : CalcTextSize(text, text_display_end, false, 0.0f);
@@ -2189,14 +2183,27 @@ void ImGui::RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, cons
     if (need_clipping)
     {
         ImVec4 fine_clip_rect(clip_min->x, clip_min->y, clip_max->x, clip_max->y);
-        window->DrawList->AddText(g.Font, g.FontSize, pos, GetColorU32(ImGuiCol_Text), text, text_display_end, 0.0f, &fine_clip_rect);
+        draw_list->AddText(NULL, 0.0f, pos, GetColorU32(ImGuiCol_Text), text, text_display_end, 0.0f, &fine_clip_rect);
     }
     else
     {
-        window->DrawList->AddText(g.Font, g.FontSize, pos, GetColorU32(ImGuiCol_Text), text, text_display_end, 0.0f, NULL);
+        draw_list->AddText(NULL, 0.0f, pos, GetColorU32(ImGuiCol_Text), text, text_display_end, 0.0f, NULL);
     }
+}
+
+void ImGui::RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, const ImVec2& align, const ImRect* clip_rect)
+{
+    // Hide anything after a '##' string
+    const char* text_display_end = FindRenderedTextEnd(text, text_end);
+    const int text_len = (int)(text_display_end - text);
+    if (text_len == 0)
+        return;
+
+    ImGuiContext& g = *GImGui;
+    ImGuiWindow* window = g.CurrentWindow;
+    RenderTextClippedEx(window->DrawList, pos_min, pos_max, text, text_display_end, text_size_if_known, align, clip_rect);
     if (g.LogEnabled)
-        LogRenderedText(&pos, text, text_display_end);
+        LogRenderedText(&pos_min, text, text_display_end);
 }
 
 // Render a rectangle shaped with optional rounding and borders
@@ -5511,6 +5518,7 @@ static const ImGuiStyleVarInfo GStyleVarInfo[] =
     { ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImGuiStyle, ScrollbarRounding) },  // ImGuiStyleVar_ScrollbarRounding
     { ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImGuiStyle, GrabMinSize) },        // ImGuiStyleVar_GrabMinSize
     { ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImGuiStyle, GrabRounding) },       // ImGuiStyleVar_GrabRounding
+    { ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImGuiStyle, TabRounding) },        // ImGuiStyleVar_TabRounding
     { ImGuiDataType_Float, 2, (ImU32)IM_OFFSETOF(ImGuiStyle, ButtonTextAlign) },    // ImGuiStyleVar_ButtonTextAlign
 };
 
@@ -5603,6 +5611,11 @@ const char* ImGui::GetStyleColorName(ImGuiCol idx)
     case ImGuiCol_ResizeGrip: return "ResizeGrip";
     case ImGuiCol_ResizeGripHovered: return "ResizeGripHovered";
     case ImGuiCol_ResizeGripActive: return "ResizeGripActive";
+    case ImGuiCol_Tab: return "Tab";
+    case ImGuiCol_TabHovered: return "TabHovered";
+    case ImGuiCol_TabActive: return "TabActive";
+    case ImGuiCol_TabUnfocused: return "TabUnfocused";
+    case ImGuiCol_TabUnfocusedActive: return "TabUnfocusedActive";
     case ImGuiCol_PlotLines: return "PlotLines";
     case ImGuiCol_PlotLinesHovered: return "PlotLinesHovered";
     case ImGuiCol_PlotHistogram: return "PlotHistogram";
@@ -9056,6 +9069,29 @@ void ImGui::ShowMetricsWindow(bool* p_open)
             ImGui::BulletText("Storage: %d bytes", window->StateStorage.Data.Size * (int)sizeof(ImGuiStorage::Pair));
             ImGui::TreePop();
         }
+
+        static void NodeTabBar(ImGuiTabBar* tab_bar)
+        {
+            // Standalone tab bars (not associated to docking/windows functionality) currently hold no discernable strings.
+            char buf[256];
+            char* p = buf;
+            const char* buf_end = buf + IM_ARRAYSIZE(buf);
+            p += ImFormatString(p, buf_end - p, "TabBar (%d tabs)%s",
+                tab_bar->Tabs.Size, (tab_bar->PrevFrameVisible < ImGui::GetFrameCount() - 2) ? " *Inactive*" : "");
+            if (ImGui::TreeNode(tab_bar, "%s", buf))
+            {
+                for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+                {
+                    const ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+                    ImGui::PushID(tab);
+                    if (ImGui::SmallButton("<")) { TabBarQueueChangeTabOrder(tab_bar, tab, -1); } ImGui::SameLine(0, 2);
+                    if (ImGui::SmallButton(">")) { TabBarQueueChangeTabOrder(tab_bar, tab, +1); } ImGui::SameLine();
+                    ImGui::Text("%02d%c Tab 0x%08X", tab_n, (tab->ID == tab_bar->SelectedTabId) ? '*' : ' ', tab->ID);
+                    ImGui::PopID();
+                }
+                ImGui::TreePop();
+            }
+        }
     };
 
     // Access private state, we are going to display the draw lists from last frame
@@ -9076,6 +9112,12 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         }
         ImGui::TreePop();
     }
+    if (ImGui::TreeNode("TabBars", "Tab Bars (%d)", g.TabBars.Data.Size))
+    {
+        for (int n = 0; n < g.TabBars.Data.Size; n++)
+            Funcs::NodeTabBar(g.TabBars.GetByIndex(n));
+        ImGui::TreePop();
+    }
     if (ImGui::TreeNode("Internal state"))
     {
         const char* input_source_names[] = { "None", "Mouse", "Nav", "NavKeyboard", "NavGamepad" }; IM_ASSERT(IM_ARRAYSIZE(input_source_names) == ImGuiInputSource_COUNT);

imgui.h

@@ -135,6 +135,8 @@ typedef int ImGuiFocusedFlags;      // -> enum ImGuiFocusedFlags_    // Flags: f
 typedef int ImGuiHoveredFlags;      // -> enum ImGuiHoveredFlags_    // Flags: for IsItemHovered(), IsWindowHovered() etc.
 typedef int ImGuiInputTextFlags;    // -> enum ImGuiInputTextFlags_  // Flags: for InputText*()
 typedef int ImGuiSelectableFlags;   // -> enum ImGuiSelectableFlags_ // Flags: for Selectable()
+typedef int ImGuiTabBarFlags;       // -> enum ImGuiTabBarFlags_     // Flags: for BeginTabBar()
+typedef int ImGuiTabItemFlags;      // -> enum ImGuiTabItemFlags_    // Flags: for BeginTabItem()
 typedef int ImGuiTreeNodeFlags;     // -> enum ImGuiTreeNodeFlags_   // Flags: for TreeNode*(),CollapsingHeader()
 typedef int ImGuiWindowFlags;       // -> enum ImGuiWindowFlags_     // Flags: for Begin*()
 typedef int (*ImGuiInputTextCallback)(ImGuiInputTextCallbackData *data);
@@ -528,6 +530,14 @@ namespace ImGui
     IMGUI_API void          SetColumnOffset(int column_index, float offset_x);                  // set position of column line (in pixels, from the left side of the contents region). pass -1 to use current column
     IMGUI_API int           GetColumnsCount();
 
+    // Tab Bars, Tabs
+    // [BETA API] API may evolve!
+    IMGUI_API bool          BeginTabBar(const char* str_id, ImGuiTabBarFlags flags = 0);        // create and append into a TabBar
+    IMGUI_API void          EndTabBar();
+    IMGUI_API bool          BeginTabItem(const char* label, bool* p_open = NULL, ImGuiTabItemFlags flags = 0);// create a Tab. Returns true if the Tab is selected.
+    IMGUI_API void          EndTabItem();                                                       // only call EndTabItem() if BeginTabItem() returns true!
+    IMGUI_API void          SetTabItemClosed(const char* tab_or_docked_window_label);           // notify TabBar or Docking system of a closed tab/window ahead (useful to reduce visual flicker on reorderable tab bars). For tab-bar: call after BeginTabBar() and before Tab submissions. Otherwise call with a window name.
+
     // Logging/Capture: all text output from interface is captured to tty/file/clipboard. By default, tree nodes are automatically opened during logging.
     IMGUI_API void          LogToTTY(int max_depth = -1);                                       // start logging to tty
     IMGUI_API void          LogToFile(int max_depth = -1, const char* filename = NULL);         // start logging to file
@@ -760,6 +770,31 @@ enum ImGuiComboFlags_
     ImGuiComboFlags_HeightMask_             = ImGuiComboFlags_HeightSmall | ImGuiComboFlags_HeightRegular | ImGuiComboFlags_HeightLarge | ImGuiComboFlags_HeightLargest
 };
 
+// Flags for ImGui::BeginTabBar()
+enum ImGuiTabBarFlags_
+{
+    ImGuiTabBarFlags_None                           = 0,
+    ImGuiTabBarFlags_Reorderable                    = 1 << 0,   // Allow manually dragging tabs to re-order them + New tabs are appended at the end of list
+    ImGuiTabBarFlags_AutoSelectNewTabs              = 1 << 1,   // Automatically select new tabs when they appear
+    ImGuiTabBarFlags_NoCloseWithMiddleMouseButton   = 1 << 2,   // Disable behavior of closing tabs (that are submitted with p_open != NULL) with middle mouse button. You can still repro this behavior on user's side with if (IsItemHovered() && IsMouseClicked(2)) *p_open = false.
+    ImGuiTabBarFlags_NoTabListPopupButton           = 1 << 3,
+    ImGuiTabBarFlags_NoTabListScrollingButtons      = 1 << 4,
+    ImGuiTabBarFlags_FittingPolicyResizeDown        = 1 << 5,   // Resize tabs when they don't fit
+    ImGuiTabBarFlags_FittingPolicyScroll            = 1 << 6,   // Add scroll buttons when tabs don't fit
+    ImGuiTabBarFlags_FittingPolicyMask_             = ImGuiTabBarFlags_FittingPolicyResizeDown | ImGuiTabBarFlags_FittingPolicyScroll,
+    ImGuiTabBarFlags_FittingPolicyDefault_          = ImGuiTabBarFlags_FittingPolicyResizeDown
+};  
+
+// Flags for ImGui::BeginTabItem()
+enum ImGuiTabItemFlags_
+{
+    ImGuiTabItemFlags_None                          = 0,
+    ImGuiTabItemFlags_UnsavedDocument               = 1 << 0,   // Append '*' to title without affecting the ID, as a convenience to avoid using the ### operator. Also: tab is selected on closure and closure is deferred by one frame to allow code to undo it without flicker.
+    ImGuiTabItemFlags_SetSelected                   = 1 << 1,   // Trigger flag to programatically make the tab selected when calling BeginTabItem()
+    ImGuiTabItemFlags_NoCloseWithMiddleMouseButton  = 1 << 2,   // Disable behavior of closing tabs (that are submitted with p_open != NULL) with middle mouse button. You can still repro this behavior on user's side with if (IsItemHovered() && IsMouseClicked(2)) *p_open = false.
+    ImGuiTabItemFlags_NoPushId                      = 1 << 3    // Don't call PushID(tab->ID)/PopID() on BeginTabItem()/EndTabItem()
+};
+
 // Flags for ImGui::IsWindowFocused()
 enum ImGuiFocusedFlags_
 {
@@ -956,6 +991,11 @@ enum ImGuiCol_
     ImGuiCol_ResizeGrip,
     ImGuiCol_ResizeGripHovered,
     ImGuiCol_ResizeGripActive,
+    ImGuiCol_Tab,
+    ImGuiCol_TabHovered,
+    ImGuiCol_TabActive,
+    ImGuiCol_TabUnfocused,
+    ImGuiCol_TabUnfocusedActive,
     ImGuiCol_PlotLines,
     ImGuiCol_PlotLinesHovered,
     ImGuiCol_PlotHistogram,
@@ -1003,6 +1043,7 @@ enum ImGuiStyleVar_
     ImGuiStyleVar_ScrollbarRounding,   // float     ScrollbarRounding
     ImGuiStyleVar_GrabMinSize,         // float     GrabMinSize
     ImGuiStyleVar_GrabRounding,        // float     GrabRounding
+    ImGuiStyleVar_TabRounding,         // float     TabRounding
     ImGuiStyleVar_ButtonTextAlign,     // ImVec2    ButtonTextAlign
     ImGuiStyleVar_COUNT
 
@@ -1114,6 +1155,8 @@ struct ImGuiStyle
     float       ScrollbarRounding;          // Radius of grab corners for scrollbar.
     float       GrabMinSize;                // Minimum width/height of a grab box for slider/scrollbar.
     float       GrabRounding;               // Radius of grabs corners rounding. Set to 0.0f to have rectangular slider grabs.
+    float       TabRounding;                // Radius of upper corners of a tab. Set to 0.0f to have rectangular tabs.
+    float       TabBorderSize;              // Thickness of border around tabs. 
     ImVec2      ButtonTextAlign;            // Alignment of button text when button is larger than text. Defaults to (0.5f,0.5f) for horizontally+vertically centered.
     ImVec2      DisplayWindowPadding;       // Window position are clamped to be visible within the display area by at least this amount. Only applies to regular windows.
     ImVec2      DisplaySafeAreaPadding;     // If you cannot see the edges of your screen (e.g. on a TV) increase the safe area padding. Apply to popups/tooltips as well regular windows. NB: Prefer configuring your TV sets correctly!

imgui_demo.cpp

@@ -40,6 +40,7 @@ Index of this file:
 // [SECTION] Example App: Simple Overlay / ShowExampleAppSimpleOverlay()
 // [SECTION] Example App: Manipulating Window Titles / ShowExampleAppWindowTitles()
 // [SECTION] Example App: Custom Rendering using ImDrawList API / ShowExampleAppCustomRendering()
+// [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
 
 */
 
@@ -102,6 +103,7 @@ Index of this file:
 #if !defined(IMGUI_DISABLE_DEMO_WINDOWS)
 
 // Forward Declarations
+static void ShowExampleAppDocuments(bool* p_open);
 static void ShowExampleAppMainMenuBar();
 static void ShowExampleAppConsole(bool* p_open);
 static void ShowExampleAppLog(bool* p_open);
@@ -168,6 +170,7 @@ static void ShowDemoWindowMisc();
 void ImGui::ShowDemoWindow(bool* p_open)
 {
     // Examples Apps (accessible from the "Examples" menu)
+    static bool show_app_documents = false;
     static bool show_app_main_menu_bar = false;
     static bool show_app_console = false;
     static bool show_app_log = false;
@@ -180,6 +183,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
     static bool show_app_window_titles = false;
     static bool show_app_custom_rendering = false;
 
+    if (show_app_documents)           ShowExampleAppDocuments(&show_app_documents);     // Process the Document app next, as it may also use a DockSpace()
     if (show_app_main_menu_bar)       ShowExampleAppMainMenuBar();
     if (show_app_console)             ShowExampleAppConsole(&show_app_console);
     if (show_app_log)                 ShowExampleAppLog(&show_app_log);
@@ -263,6 +267,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
             ImGui::MenuItem("Simple overlay", NULL, &show_app_simple_overlay);
             ImGui::MenuItem("Manipulating window titles", NULL, &show_app_window_titles);
             ImGui::MenuItem("Custom rendering", NULL, &show_app_custom_rendering);
+            ImGui::MenuItem("Documents", NULL, &show_app_documents);
             ImGui::EndMenu();
         }
         if (ImGui::BeginMenu("Help"))
@@ -1698,6 +1703,76 @@ static void ShowDemoWindowLayout()
         ImGui::TreePop();
     }
 
+    if (ImGui::TreeNode("Tabs"))
+    {
+        if (ImGui::TreeNode("Basic"))
+        {
+            ImGuiTabBarFlags tab_bar_flags = ImGuiTabBarFlags_None;
+            if (ImGui::BeginTabBar("MyTabBar", tab_bar_flags))
+            {
+                if (ImGui::BeginTabItem("Avocado"))
+                {
+                    ImGui::Text("This is the Avocado tab!\nblah blah blah blah blah");
+                    ImGui::EndTabItem();
+                }
+                if (ImGui::BeginTabItem("Broccoli"))
+                {
+                    ImGui::Text("This is the Broccoli tab!\nblah blah blah blah blah");
+                    ImGui::EndTabItem();
+                }
+                if (ImGui::BeginTabItem("Cucumber"))
+                {
+                    ImGui::Text("This is the Cucumber tab!\nblah blah blah blah blah");
+                    ImGui::EndTabItem();
+                }
+                ImGui::EndTabBar();
+            }
+            ImGui::Separator();
+            ImGui::TreePop();
+        }
+
+        if (ImGui::TreeNode("Advanced & Close Button"))
+        {
+            // Expose a couple of the available flags. In most cases you may just call BeginTabBar() with no flags (0).
+            static ImGuiTabBarFlags tab_bar_flags = ImGuiTabBarFlags_Reorderable;
+            ImGui::CheckboxFlags("ImGuiTabBarFlags_Reorderable", (unsigned int*)&tab_bar_flags, ImGuiTabBarFlags_Reorderable);
+            ImGui::CheckboxFlags("ImGuiTabBarFlags_AutoSelectNewTabs", (unsigned int*)&tab_bar_flags, ImGuiTabBarFlags_AutoSelectNewTabs);
+            ImGui::CheckboxFlags("ImGuiTabBarFlags_NoCloseWithMiddleMouseButton", (unsigned int*)&tab_bar_flags, ImGuiTabBarFlags_NoCloseWithMiddleMouseButton);
+            if ((tab_bar_flags & ImGuiTabBarFlags_FittingPolicyMask_) == 0)
+                tab_bar_flags |= ImGuiTabBarFlags_FittingPolicyDefault_;
+            if (ImGui::CheckboxFlags("ImGuiTabBarFlags_FittingPolicyResizeDown", (unsigned int*)&tab_bar_flags, ImGuiTabBarFlags_FittingPolicyResizeDown))
+                tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyResizeDown);
+            if (ImGui::CheckboxFlags("ImGuiTabBarFlags_FittingPolicyScroll", (unsigned int*)&tab_bar_flags, ImGuiTabBarFlags_FittingPolicyScroll))
+                tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyScroll);
+
+            // Tab Bar
+            const char* names[4] = { "Artichoke", "Beetroot", "Celery", "Daikon" };
+            static bool opened[4] = { true, true, true, true }; // Persistent user state
+            for (int n = 0; n < IM_ARRAYSIZE(opened); n++)
+            {
+                if (n > 0) { ImGui::SameLine(); }
+                ImGui::Checkbox(names[n], &opened[n]);
+            }
+
+            // Passing a bool* to BeginTabItem() is similar to passing one to Begin(): the underlying bool will be set to false when the tab is closed.
+            if (ImGui::BeginTabBar("MyTabBar", tab_bar_flags))
+            {
+                for (int n = 0; n < IM_ARRAYSIZE(opened); n++)
+                    if (opened[n] && ImGui::BeginTabItem(names[n], &opened[n]))
+                    {
+                        ImGui::Text("This is the %s tab!", names[n]);
+                        if (n & 1)
+                            ImGui::Text("I am an odd tab.");
+                        ImGui::EndTabItem();
+                    }
+                ImGui::EndTabBar();
+            }
+            ImGui::Separator();
+            ImGui::TreePop();
+        }
+        ImGui::TreePop();
+    }
+
     if (ImGui::TreeNode("Groups"))
     {
         ImGui::TextWrapped("(Using ImGui::BeginGroup()/EndGroup() to layout items. BeginGroup() basically locks the horizontal position. EndGroup() bundles the whole group so that you can use functions such as IsItemHovered() on it.)");
@@ -2679,12 +2754,14 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
         ImGui::SliderFloat("ChildBorderSize", &style.ChildBorderSize, 0.0f, 1.0f, "%.0f");
         ImGui::SliderFloat("PopupBorderSize", &style.PopupBorderSize, 0.0f, 1.0f, "%.0f");
         ImGui::SliderFloat("FrameBorderSize", &style.FrameBorderSize, 0.0f, 1.0f, "%.0f");
+        ImGui::SliderFloat("TabBorderSize", &style.TabBorderSize, 0.0f, 1.0f, "%.0f");
         ImGui::Text("Rounding");
         ImGui::SliderFloat("WindowRounding", &style.WindowRounding, 0.0f, 14.0f, "%.0f");
         ImGui::SliderFloat("ChildRounding", &style.ChildRounding, 0.0f, 16.0f, "%.0f");
         ImGui::SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 12.0f, "%.0f");
         ImGui::SliderFloat("ScrollbarRounding", &style.ScrollbarRounding, 0.0f, 12.0f, "%.0f");
         ImGui::SliderFloat("GrabRounding", &style.GrabRounding, 0.0f, 12.0f, "%.0f");
+        ImGui::SliderFloat("TabRounding", &style.TabRounding, 0.0f, 12.0f, "%.0f");
         ImGui::Text("Alignment");
         ImGui::SliderFloat2("WindowTitleAlign", (float*)&style.WindowTitleAlign, 0.0f, 1.0f, "%.2f");
         ImGui::SliderFloat2("ButtonTextAlign", (float*)&style.ButtonTextAlign, 0.0f, 1.0f, "%.2f"); ImGui::SameLine(); ShowHelpMarker("Alignment applies when a button is larger than its text content.");
@@ -3758,6 +3835,271 @@ static void ShowExampleAppCustomRendering(bool* p_open)
         if (adding_preview)
             points.pop_back();
     }
+}
+
+//-----------------------------------------------------------------------------
+// [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
+//-----------------------------------------------------------------------------
+
+// Simplified structure to mimic a Document model
+struct MyDocument
+{
+    const char* Name;           // Document title
+    bool        Open;           // Set when the document is open (in this demo, we keep an array of all available documents to simplify the demo)
+    bool        OpenPrev;       // Copy of Open from last update.
+    bool        Dirty;          // Set when the document has been modified
+    bool        WantClose;      // Set when the document 
+    ImVec4      Color;          // An arbitrary variable associated to the document
+
+    MyDocument(const char* name, bool open = true, const ImVec4& color = ImVec4(1.0f,1.0f,1.0f,1.0f))
+    { 
+        Name = name; 
+        Open = OpenPrev = open; 
+        Dirty = false; 
+        WantClose = false; 
+        Color = color; 
+    }
+    void DoOpen()       { Open = true; }
+    void DoQueueClose() { WantClose = true; }
+    void DoForceClose() { Open = false; Dirty = false; }
+    void DoSave()       { Dirty = false; }
+
+    // Display dummy contents for the Document
+    static void DisplayContents(MyDocument* doc)
+    {
+        ImGui::PushID(doc);
+        ImGui::Text("Document \"%s\"", doc->Name);
+        ImGui::PushStyleColor(ImGuiCol_Text, doc->Color);
+        ImGui::TextWrapped("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.");
+        ImGui::PopStyleColor();
+        if (ImGui::Button("Modify", ImVec2(100, 0)))
+            doc->Dirty = true;
+        ImGui::SameLine();
+        if (ImGui::Button("Save", ImVec2(100, 0)))
+            doc->DoSave();
+        ImGui::ColorEdit3("color", &doc->Color.x);  // Useful to test drag and drop and hold-dragged-to-open-tab behavior.
+        ImGui::PopID();
+    }
+
+    // Display context menu for the Document
+    static void DisplayContextMenu(MyDocument* doc)
+    {
+        if (!ImGui::BeginPopupContextItem())
+            return;
+
+        char buf[256];
+        sprintf(buf, "Save %s", doc->Name);
+        if (ImGui::MenuItem(buf, "CTRL+S", false, doc->Open))
+            doc->DoSave();
+        if (ImGui::MenuItem("Close", "CTRL+W", false, doc->Open))
+            doc->DoQueueClose();
+        ImGui::EndPopup();
+    }
+};
+
+struct ExampleAppDocuments
+{
+    ImVector<MyDocument> Documents;
+
+    ExampleAppDocuments()
+    {
+        Documents.push_back(MyDocument("Lettuce",             true,  ImVec4(0.4f, 0.8f, 0.4f, 1.0f)));
+        Documents.push_back(MyDocument("Eggplant",            true,  ImVec4(0.8f, 0.5f, 1.0f, 1.0f)));
+        Documents.push_back(MyDocument("Carrot",              true,  ImVec4(1.0f, 0.8f, 0.5f, 1.0f)));
+        Documents.push_back(MyDocument("Tomato",              false, ImVec4(1.0f, 0.3f, 0.4f, 1.0f)));
+        Documents.push_back(MyDocument("A Rather Long Title", false));
+        Documents.push_back(MyDocument("Some Document",       false));
+    }
+};
+
+// [Optional] Notify the system of Tabs/Windows closure that happened outside the regular tab interface.
+// If a tab has been closed programmatically (aka closed from another source such as the Checkbox() in the demo, as opposed
+// to clicking on the regular tab closing button) and stops being submitted, it will take a frame for the tab bar to notice its absence. 
+// During this frame there will be a gap in the tab bar, and if the tab that has disappeared was the selected one, the tab bar 
+// will report no selected tab during the frame. This will effectively give the impression of a flicker for one frame.
+// We call SetTabItemClosed() to manually notify the Tab Bar or Docking system of removed tabs to avoid this glitch.
+// Note that this completely optional, and only affect tab bars with the ImGuiTabBarFlags_Reorderable flag.
+static void NotifyOfDocumentsClosedElsewhere(ExampleAppDocuments& app)
+{
+    for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+    {
+        MyDocument* doc = &app.Documents[doc_n];
+        if (!doc->Open && doc->OpenPrev)
+            ImGui::SetTabItemClosed(doc->Name);
+        doc->OpenPrev = doc->Open;
+    }
+}
+
+void ShowExampleAppDocuments(bool* p_open)
+{
+    static ExampleAppDocuments app;
+
+    ImGui::Begin("Examples: Documents", p_open, ImGuiWindowFlags_MenuBar);
+
+    // Options
+    static bool opt_reorderable = true;
+    static ImGuiTabBarFlags opt_fitting_flags = ImGuiTabBarFlags_FittingPolicyDefault_;
+
+    // Menu
+    if (ImGui::BeginMenuBar())
+    {
+        if (ImGui::BeginMenu("File"))
+        {
+            int open_count = 0;
+            for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+                open_count += app.Documents[doc_n].Open ? 1 : 0;
+
+            if (ImGui::BeginMenu("Open", open_count < app.Documents.Size))
+            {
+                for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+                {
+                    MyDocument* doc = &app.Documents[doc_n];
+                    if (!doc->Open)
+                        if (ImGui::MenuItem(doc->Name))
+                            doc->DoOpen();
+                }
+                ImGui::EndMenu();
+            }
+            if (ImGui::MenuItem("Close All Documents", NULL, false, open_count > 0))
+                for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+                    app.Documents[doc_n].DoQueueClose();
+            if (ImGui::MenuItem("Exit", "Alt+F4")) {}
+            ImGui::EndMenu();
+        }
+        ImGui::EndMenuBar();
+    }
+
+    // [Debug] List documents with one checkbox for each
+    for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+    {
+        MyDocument* doc = &app.Documents[doc_n];
+        if (doc_n > 0)
+            ImGui::SameLine();
+        ImGui::PushID(doc);
+        if (ImGui::Checkbox(doc->Name, &doc->Open))
+            if (!doc->Open)
+                doc->DoForceClose();
+        ImGui::PopID();
+    }
+
+    ImGui::Separator();
+
+    // Submit Tab Bar and Tabs
+    {
+        ImGuiTabBarFlags tab_bar_flags = (opt_fitting_flags) | (opt_reorderable ? ImGuiTabBarFlags_Reorderable : 0);
+        if (ImGui::BeginTabBar("##tabs", tab_bar_flags))
+        {
+            if (opt_reorderable)
+                NotifyOfDocumentsClosedElsewhere(app);
+
+            // [DEBUG] Stress tests
+            //if ((ImGui::GetFrameCount() % 30) == 0) docs[1].Open ^= 1;            // [DEBUG] Automatically show/hide a tab. Test various interactions e.g. dragging with this on.
+            //if (ImGui::GetIO().KeyCtrl) ImGui::SetTabItemSelected(docs[1].Name);  // [DEBUG] Test SetTabItemSelected(), probably not very useful as-is anyway..
+
+            // Submit Tabs
+            for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+            {
+                MyDocument* doc = &app.Documents[doc_n];
+                if (!doc->Open)
+                    continue;
+
+                ImGuiTabItemFlags tab_flags = (doc->Dirty ? ImGuiTabItemFlags_UnsavedDocument : 0);
+                bool visible = ImGui::BeginTabItem(doc->Name, &doc->Open, tab_flags);
+
+                // Cancel attempt to close when unsaved add to save queue so we can display a popup.
+                if (!doc->Open && doc->Dirty)
+                {
+                    doc->Open = true;
+                    doc->DoQueueClose();
+                }
+
+                MyDocument::DisplayContextMenu(doc);
+                if (visible)
+                {
+                    MyDocument::DisplayContents(doc);
+                    ImGui::EndTabItem();
+                }
+            }
+
+            ImGui::EndTabBar();
+        }
+    }
+
+    // Update closing queue
+    static ImVector<MyDocument*> close_queue;
+    if (close_queue.empty())
+    {
+        // Close queue is locked once we started a popup
+        for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+        {
+            MyDocument* doc = &app.Documents[doc_n];
+            if (doc->WantClose)
+            {
+                doc->WantClose = false;
+                close_queue.push_back(doc);
+            }
+        }
+    }
+
+    // Display closing confirmation UI
+    if (!close_queue.empty())
+    {
+        int close_queue_unsaved_documents = 0;
+        for (int n = 0; n < close_queue.Size; n++)
+            if (close_queue[n]->Dirty)
+                close_queue_unsaved_documents++;
+
+        if (close_queue_unsaved_documents == 0)
+        {
+            // Close documents when all are unsaved
+            for (int n = 0; n < close_queue.Size; n++)
+                close_queue[n]->DoForceClose();
+            close_queue.clear();
+        }
+        else
+        {
+            if (!ImGui::IsPopupOpen("Save?"))
+                ImGui::OpenPopup("Save?");
+            if (ImGui::BeginPopupModal("Save?"))
+            {
+                ImGui::Text("Save change to the following items?");
+                ImGui::PushItemWidth(-1.0f);
+                ImGui::ListBoxHeader("##", close_queue_unsaved_documents, 6);
+                for (int n = 0; n < close_queue.Size; n++)
+                    if (close_queue[n]->Dirty)
+                        ImGui::Text("%s", close_queue[n]->Name);
+                ImGui::ListBoxFooter();
+
+                if (ImGui::Button("Yes", ImVec2(80, 0)))
+                {
+                    for (int n = 0; n < close_queue.Size; n++)
+                    {
+                        if (close_queue[n]->Dirty)
+                            close_queue[n]->DoSave();
+                        close_queue[n]->DoForceClose();
+                    }
+                    close_queue.clear();
+                    ImGui::CloseCurrentPopup();
+                }
+                ImGui::SameLine();
+                if (ImGui::Button("No", ImVec2(80, 0)))
+                {
+                    for (int n = 0; n < close_queue.Size; n++)
+                        close_queue[n]->DoForceClose();
+                    close_queue.clear();
+                    ImGui::CloseCurrentPopup();
+                }
+                ImGui::SameLine();
+                if (ImGui::Button("Cancel", ImVec2(80, 0)))
+                {
+                    close_queue.clear();
+                    ImGui::CloseCurrentPopup();
+                }
+                ImGui::EndPopup();
+            }
+        }
+    }
+
     ImGui::End();
 }
 

imgui_draw.cpp

@@ -205,6 +205,11 @@ void ImGui::StyleColorsDark(ImGuiStyle* dst)
     colors[ImGuiCol_ResizeGrip]             = ImVec4(0.26f, 0.59f, 0.98f, 0.25f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.26f, 0.59f, 0.98f, 0.95f);
+    colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.80f);
+    colors[ImGuiCol_TabHovered]             = colors[ImGuiCol_HeaderHovered];
+    colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
+    colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
+    colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.61f, 0.61f, 0.61f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -255,6 +260,11 @@ void ImGui::StyleColorsClassic(ImGuiStyle* dst)
     colors[ImGuiCol_ResizeGrip]             = ImVec4(1.00f, 1.00f, 1.00f, 0.16f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.78f, 0.82f, 1.00f, 0.60f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.78f, 0.82f, 1.00f, 0.90f);
+    colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.80f);
+    colors[ImGuiCol_TabHovered]             = colors[ImGuiCol_HeaderHovered];
+    colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
+    colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
+    colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_PlotLines]              = ImVec4(1.00f, 1.00f, 1.00f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -306,6 +316,11 @@ void ImGui::StyleColorsLight(ImGuiStyle* dst)
     colors[ImGuiCol_ResizeGrip]             = ImVec4(0.80f, 0.80f, 0.80f, 0.56f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.26f, 0.59f, 0.98f, 0.95f);
+    colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.90f);
+    colors[ImGuiCol_TabHovered]             = colors[ImGuiCol_HeaderHovered];
+    colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
+    colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
+    colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -2821,6 +2836,7 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
 // - RenderMouseCursor()
 // - RenderArrowPointingAt()
 // - RenderRectFilledRangeH()
+// - RenderPixelEllipsis()
 //-----------------------------------------------------------------------------
 
 void ImGui::RenderMouseCursor(ImDrawList* draw_list, ImVec2 pos, float scale, ImGuiMouseCursor mouse_cursor)
@@ -2929,6 +2945,15 @@ void ImGui::RenderRectFilledRangeH(ImDrawList* draw_list, const ImRect& rect, Im
     draw_list->PathFillConvex(col);
 }
 
+// FIXME: Rendering an ellipsis "..." is a surprisingly tricky problem for us... we cannot rely on font glyph having it, 
+// and regular dot are typically too wide. If we render a dot/shape ourselves it comes with the risk that it wouldn't match 
+// the boldness or positioning of what the font uses...
+void ImGui::RenderPixelEllipsis(ImDrawList* draw_list, ImFont* font, ImVec2 pos, int count, ImU32 col)
+{
+    pos.y += (float)(int)(font->DisplayOffset.y + font->Ascent + 0.5f - 1.0f);
+    for (int dot_n = 0; dot_n < count; dot_n++)
+        draw_list->AddRectFilled(ImVec2(pos.x + dot_n * 2.0f, pos.y), ImVec2(pos.x + dot_n * 2.0f + 1.0f, pos.y + 1.0f), col);
+}
 
 //-----------------------------------------------------------------------------
 // [SECTION] Decompression code

imgui_internal.h

@@ -49,6 +49,8 @@ struct ImGuiNextWindowData;         // Storage for SetNexWindow** functions
 struct ImGuiPopupRef;               // Storage for current popup stack
 struct ImGuiSettingsHandler;        // Storage for one type registered in the .ini file
 struct ImGuiStyleMod;               // Stacked style modifier, backup of modified data so we can restore it
+struct ImGuiTabBar;                 // Storage for a tab bar
+struct ImGuiTabItem;                // Storage for a tab item (within a tab bar)
 struct ImGuiWindow;                 // Storage for one window
 struct ImGuiWindowTempData;         // Temporary storage for one window (that's the data which in theory we could ditch at the end of the frame)
 struct ImGuiWindowSettings;         // Storage for window settings stored in .ini file (we keep one of those even if the actual window wasn't instanced during this session)
@@ -679,6 +681,12 @@ struct ImGuiNextWindowData
     }
 };
 
+struct ImGuiTabBarSortItem
+{
+    int         Index;
+    float       Width;
+};
+
 //-----------------------------------------------------------------------------
 // Main imgui context
 //-----------------------------------------------------------------------------
@@ -804,6 +812,11 @@ struct ImGuiContext
     ImVector<unsigned char> DragDropPayloadBufHeap;             // We don't expose the ImVector<> directly
     unsigned char           DragDropPayloadBufLocal[8];         // Local buffer for small payloads
 
+    // Tab bars
+    ImPool<ImGuiTabBar>     TabBars;
+    ImVector<ImGuiTabBar*>  CurrentTabBar;
+    ImVector<ImGuiTabBarSortItem>   TabSortByWidthBuffer;
+
     // Widget state
     ImGuiInputTextState     InputTextState;
     ImFont                  InputTextPasswordFont;
@@ -1154,6 +1167,59 @@ struct ImGuiItemHoveredDataBackup
     void Restore() const    { ImGuiWindow* window = GImGui->CurrentWindow; window->DC.LastItemId = LastItemId; window->DC.LastItemStatusFlags = LastItemStatusFlags; window->DC.LastItemRect = LastItemRect; window->DC.LastItemDisplayRect = LastItemDisplayRect; }
 };
 
+//-----------------------------------------------------------------------------
+// Tab Bar, Tab Item
+//-----------------------------------------------------------------------------
+
+enum ImGuiTabBarFlagsPrivate_
+{
+    ImGuiTabBarFlags_DockNode                   = 1 << 20,  // [Docking: Unused in Master Branch] Part of a dock node
+    ImGuiTabBarFlags_DockNodeIsDockSpace        = 1 << 21,  // [Docking: Unused in Master Branch] Part of an explicit dockspace node node
+    ImGuiTabBarFlags_IsFocused                  = 1 << 22,
+    ImGuiTabBarFlags_SaveSettings               = 1 << 23   // FIXME: Settings are handled by the docking system, this only request the tab bar to mark settings dirty when reordering tabs
+};
+
+// Storage for one active tab item (sizeof() 26~32 bytes)
+struct ImGuiTabItem
+{
+    ImGuiID             ID;
+    ImGuiTabItemFlags   Flags;
+    int                 LastFrameVisible;
+    int                 LastFrameSelected;      // This allows us to infer an ordered list of the last activated tabs with little maintenance
+    float               Offset;                 // Position relative to beginning of tab
+    float               Width;                  // Width currently displayed
+    float               WidthContents;          // Width of actual contents, stored during BeginTabItem() call
+
+    ImGuiTabItem()      { ID = Flags = 0; LastFrameVisible = LastFrameSelected = -1; Offset = Width = WidthContents = 0.0f; }
+};
+
+// Storage for a tab bar (sizeof() 92~96 bytes)
+struct ImGuiTabBar
+{
+    ImVector<ImGuiTabItem> Tabs;
+    ImGuiID             ID;                     // Zero for tab-bars used by docking
+    ImGuiID             SelectedTabId;          // Selected tab
+    ImGuiID             NextSelectedTabId;
+    ImGuiID             VisibleTabId;           // Can occasionally be != SelectedTabId (e.g. when previewing contents for CTRL+TAB preview)
+    int                 CurrFrameVisible;
+    int                 PrevFrameVisible;
+    ImRect              BarRect;
+    float               ContentsHeight;
+    float               OffsetMax;              // Distance from BarRect.Min.x, locked during layout
+    float               OffsetNextTab;          // Distance from BarRect.Min.x, incremented with each BeginTabItem() call, not used if ImGuiTabBarFlags_Reorderable if set.
+    float               ScrollingAnim;
+    float               ScrollingTarget;
+    ImGuiTabBarFlags    Flags;
+    ImGuiID             ReorderRequestTabId;
+    int                 ReorderRequestDir;
+    bool                WantLayout;
+    bool                VisibleTabWasSubmitted;
+    short               LastTabItemIdx;         // For BeginTabItem()/EndTabItem()
+
+    ImGuiTabBar();
+    int                 GetTabOrder(const ImGuiTabItem* tab) const { return Tabs.index_from_pointer(tab); }
+};
+
 //-----------------------------------------------------------------------------
 // Internal API
 // No guarantee of forward compatibility here.
@@ -1270,12 +1336,24 @@ namespace ImGui
     IMGUI_API void          EndColumns();                                                             // close columns
     IMGUI_API void          PushColumnClipRect(int column_index = -1);
 
+    // Tab Bars
+    IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags);
+    IMGUI_API ImGuiTabItem* TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id);
+    IMGUI_API void          TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id);
+    IMGUI_API void          TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
+    IMGUI_API void          TabBarQueueChangeTabOrder(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, int dir);
+    IMGUI_API bool          TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags);
+    IMGUI_API ImVec2        TabItemCalcSize(const char* label, bool has_close_button);
+    IMGUI_API void          TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImU32 col);
+    IMGUI_API bool          TabItemLabelAndCloseButton(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, const char* label, ImGuiID tab_id, ImGuiID close_button_id);
+
     // Render helpers
     // AVOID USING OUTSIDE OF IMGUI.CPP! NOT FOR PUBLIC CONSUMPTION. THOSE FUNCTIONS ARE A MESS. THEIR SIGNATURE AND BEHAVIOR WILL CHANGE, THEY NEED TO BE REFACTORED INTO SOMETHING DECENT.
     // NB: All position are in absolute pixels coordinates (we are never using window coordinates internally)
     IMGUI_API void          RenderText(ImVec2 pos, const char* text, const char* text_end = NULL, bool hide_text_after_hash = true);
     IMGUI_API void          RenderTextWrapped(ImVec2 pos, const char* text, const char* text_end, float wrap_width);
     IMGUI_API void          RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, const ImVec2& align = ImVec2(0,0), const ImRect* clip_rect = NULL);
+    IMGUI_API void          RenderTextClippedEx(ImDrawList* draw_list, const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, const ImVec2& align = ImVec2(0, 0), const ImRect* clip_rect = NULL);
     IMGUI_API void          RenderFrame(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, bool border = true, float rounding = 0.0f);
     IMGUI_API void          RenderFrameBorder(ImVec2 p_min, ImVec2 p_max, float rounding = 0.0f);
     IMGUI_API void          RenderColorRectWithAlphaCheckerboard(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, float grid_step, ImVec2 grid_off, float rounding = 0.0f, int rounding_corners_flags = ~0);
@@ -1290,6 +1368,7 @@ namespace ImGui
     IMGUI_API void          RenderMouseCursor(ImDrawList* draw_list, ImVec2 pos, float scale, ImGuiMouseCursor mouse_cursor = ImGuiMouseCursor_Arrow);
     IMGUI_API void          RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half_sz, ImGuiDir direction, ImU32 col);
     IMGUI_API void          RenderRectFilledRangeH(ImDrawList* draw_list, const ImRect& rect, ImU32 col, float x_start_norm, float x_end_norm, float rounding);
+    IMGUI_API void          RenderPixelEllipsis(ImDrawList* draw_list, ImFont* font, ImVec2 pos, int count, ImU32 col);
 
     // Widgets
     IMGUI_API bool          ButtonEx(const char* label, const ImVec2& size_arg = ImVec2(0,0), ImGuiButtonFlags flags = 0);