Merge branch 'master' into docking

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

docs/CHANGELOG.txt

@@ -106,6 +106,13 @@ Breaking Changes:
 - Renamed SetNextTreeNodeOpen() to SetNextItemOpen(). Kept inline redirection function (will obsolete).
 
 Other Changes:
+- Window: clarified behavior of SetNextWindowContentSize(). Content size is defined as the size available
+  after removal of WindowPadding on each sides. So SetNextWindowContentSize(ImVec2(100,100)) + auto-resize
+  will always allow submitting a 100x100 item without creating a scrollbar, regarding of WindowPadding.
+  The exact meaning of ContentSize for decorated windows was previously ill-defined.
+- Window: Fixed auto-resize with AlwaysVerticalScrollbar or AlwaysHorizontalScrollbar flags.
+- Window: Fixed one case where auto-resize by double-clicking the resize grip would make either scrollbar
+  appear for a single frame after the resize.
 - Columns: Fixed Separator from creating an extraneous draw command. (#125)
 - Columns: Fixed Selectable with SpanAllColumns flag from creating an extraneous draw command. (#125)
 - Separator: Revert 1.70 "Declare its thickness (1.0f) to the layout" change. It's not incorrect
@@ -121,7 +128,8 @@ Other Changes:
 - ColorEdit: Fixed the color picker popup only displaying inputs as HSV instead of showing multiple
   options. (#2587, broken in 1.69 by #2384).
 - CollapsingHeader: Better clipping when a close button is enabled and it overlaps the label. (#600)
-- Scrollbar: Very minor bounding box adjustment to cope with various border size.
+- Scrollbar: Minor bounding box adjustment to cope with various border size.
+- Scrollbar, Style: Changed default style.ScrollbarSize from 16 to 14.
 - Combo: Fixed rounding not applying with the ImGuiComboFlags_NoArrowButton flag. (#2607) [@DucaRii]
 - Nav: Fixed gamepad/keyboard moving of window affecting contents size incorrectly, sometimes leading
   to scrollbars appearing during the movement.
@@ -129,6 +137,12 @@ Other Changes:
   frame as clearing the focus. This was in most noticeable in back-ends such as Glfw and SDL which
   emits key release events when focusing another viewport, leading to Alt+clicking on void on another
   viewport triggering the issue. (#2609)
+- TreeNode, CollapsingHeader: Fixed highlight frame not covering horizontal area fully when using
+  horizontal scrolling. (#2211, #2579)
+- TabBar: Fixed BeginTabBar() within a window with horizontal scrolling from creating a feedback
+  loop with the horizontal contents size.
+- Columns: Fixed Columns() within a window with horizontal scrolling from not covering the full
+  horizontal area (previously only worked with an explicit contents size). (#125)
 - Style: Added style.WindowMenuButtonPosition (left/right, defaults to ImGuiDir_Left) to move the
   collapsing/docking button to the other side of the title bar.
 - Style: Made window close button cross slightly smaller.

docs/TODO.txt

@@ -70,6 +70,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - widgets: selectable: a way to visualize partial/mixed selection (e.g. parent tree node has children with mixed selection)
  - widgets: checkbox: checkbox with custom glyph inside frame.
  - widgets: coloredit: keep reporting as active when picker is on?
+ - widgets: group/scalarn functions: expose more per-component information. e.g. store NextItemData.ComponentIdx set by scalarn function, groups can expose them back somehow.
 
  - input text: clean up the mess caused by converting UTF-8 <> wchar. the code is rather inefficient right now and super fragile.
  - input text: reorganize event handling, allow CharFilter to modify buffers, allow multiple events? (#541)
@@ -258,6 +259,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - style: a concept of "compact style" that the end-user can easily rely on (e.g. PushStyleCompact()?) that maps to other settings? avoid implementing duplicate helpers such as SmallCheckbox(), etc.
  - style: try to make PushStyleVar() more robust to incorrect parameters (to be more friendly to edit & continues situation).
  - style: global scale setting.
+ - style: FramePadding could be different for up vs down (#584)
  - style: WindowPadding needs to be EVEN as the 0.5 multiplier used on this value probably have a subtle effect on clip rectangle
  - style: have a more global HSV setter (e.g. alter hue on all elements). consider replacing active/hovered by offset in HSV space? (#438, #707, #1223)
  - style: gradients fill (#1223) ~ 2 bg colors for each fill? tricky with rounded shapes and using textures for corners.

imgui.h

@@ -282,7 +282,7 @@ namespace ImGui
     IMGUI_API void          SetNextWindowPos(const ImVec2& pos, ImGuiCond cond = 0, const ImVec2& pivot = ImVec2(0,0)); // set next window position. call before Begin(). use pivot=(0.5f,0.5f) to center on given point, etc.
     IMGUI_API void          SetNextWindowSize(const ImVec2& size, ImGuiCond cond = 0);                  // set next window size. set axis to 0.0f to force an auto-fit on this axis. call before Begin()
     IMGUI_API void          SetNextWindowSizeConstraints(const ImVec2& size_min, const ImVec2& size_max, ImGuiSizeCallback custom_callback = NULL, void* custom_callback_data = NULL); // set next window size limits. use -1,-1 on either X/Y axis to preserve the current size. Sizes will be rounded down. Use callback to apply non-trivial programmatic constraints.
-    IMGUI_API void          SetNextWindowContentSize(const ImVec2& size);                               // set next window content size (~ enforce the range of scrollbars). not including window decorations (title bar, menu bar, etc.). set an axis to 0.0f to leave it automatic. call before Begin()
+    IMGUI_API void          SetNextWindowContentSize(const ImVec2& size);                               // set next window content size (~ scrollable client area, which enforce the range of scrollbars). Not including window decorations (title bar, menu bar, etc.) nor WindowPadding. set an axis to 0.0f to leave it automatic. call before Begin()
     IMGUI_API void          SetNextWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                 // set next window collapsed state. call before Begin()
     IMGUI_API void          SetNextWindowFocus();                                                       // set next window to be focused / front-most. call before Begin()
     IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                          // set next window background color alpha. helper to easily modify ImGuiCol_WindowBg/ChildBg/PopupBg. you may also use ImGuiWindowFlags_NoBackground.
@@ -831,7 +831,7 @@ enum ImGuiTreeNodeFlags_
 
     // Obsolete names (will be removed)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    , ImGuiTreeNodeFlags_AllowOverlapMode = ImGuiTreeNodeFlags_AllowItemOverlap
+    , ImGuiTreeNodeFlags_AllowOverlapMode = ImGuiTreeNodeFlags_AllowItemOverlap // [renamed in 1.53]
 #endif
 };
 
@@ -842,7 +842,7 @@ enum ImGuiSelectableFlags_
     ImGuiSelectableFlags_DontClosePopups    = 1 << 0,   // Clicking this don't close parent popup window
     ImGuiSelectableFlags_SpanAllColumns     = 1 << 1,   // Selectable frame can span all columns (text will still fit in current column)
     ImGuiSelectableFlags_AllowDoubleClick   = 1 << 2,   // Generate press events on double clicks too
-    ImGuiSelectableFlags_Disabled           = 1 << 3    // Cannot be selected, display greyed out text
+    ImGuiSelectableFlags_Disabled           = 1 << 3    // Cannot be selected, display grayed out text
 };
 
 // Flags for ImGui::BeginCombo()
@@ -1178,7 +1178,8 @@ enum ImGuiStyleVar_
 
     // Obsolete names (will be removed)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    , ImGuiStyleVar_Count_ = ImGuiStyleVar_COUNT, ImGuiStyleVar_ChildWindowRounding = ImGuiStyleVar_ChildRounding
+    , ImGuiStyleVar_Count_ = ImGuiStyleVar_COUNT                        // [renamed in 1.60]
+    , ImGuiStyleVar_ChildWindowRounding = ImGuiStyleVar_ChildRounding   // [renamed in 1.53]
 #endif
 };
 
@@ -1223,7 +1224,7 @@ enum ImGuiColorEditFlags_
 
     // Obsolete names (will be removed)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    , ImGuiColorEditFlags_RGB = ImGuiColorEditFlags_DisplayRGB, ImGuiColorEditFlags_HSV = ImGuiColorEditFlags_DisplayHSV, ImGuiColorEditFlags_HEX = ImGuiColorEditFlags_DisplayHex
+    , ImGuiColorEditFlags_RGB = ImGuiColorEditFlags_DisplayRGB, ImGuiColorEditFlags_HSV = ImGuiColorEditFlags_DisplayHSV, ImGuiColorEditFlags_HEX = ImGuiColorEditFlags_DisplayHex  // [renamed in 1.69]
 #endif
 };
 
@@ -1244,7 +1245,7 @@ enum ImGuiMouseCursor_
 
     // Obsolete names (will be removed)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    , ImGuiMouseCursor_Count_ = ImGuiMouseCursor_COUNT
+    , ImGuiMouseCursor_Count_ = ImGuiMouseCursor_COUNT      // [renamed in 1.60]
 #endif
 };
 
@@ -1260,7 +1261,7 @@ enum ImGuiCond_
 
     // Obsolete names (will be removed)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    , ImGuiSetCond_Always = ImGuiCond_Always, ImGuiSetCond_Once = ImGuiCond_Once, ImGuiSetCond_FirstUseEver = ImGuiCond_FirstUseEver, ImGuiSetCond_Appearing = ImGuiCond_Appearing
+    , ImGuiSetCond_Always = ImGuiCond_Always, ImGuiSetCond_Once = ImGuiCond_Once, ImGuiSetCond_FirstUseEver = ImGuiCond_FirstUseEver, ImGuiSetCond_Appearing = ImGuiCond_Appearing  // [renamed in 1.51]
 #endif
 };
 
@@ -1628,7 +1629,6 @@ namespace ImGui
 {
     // OBSOLETED in 1.71 (from May 2019)
     static inline void SetNextTreeNodeOpen(bool open, ImGuiCond cond = 0)   { SetNextItemOpen(open, cond); }
-
     // OBSOLETED in 1.70 (from May 2019)
     static inline float GetContentRegionAvailWidth()          { return GetContentRegionAvail().x; }
     // OBSOLETED in 1.69 (from Mar 2019)
@@ -1663,7 +1663,7 @@ namespace ImGui
     static inline bool  IsMouseHoveringAnyWindow()            { return IsWindowHovered(ImGuiHoveredFlags_AnyWindow); }
     static inline bool  IsMouseHoveringWindow()               { return IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem); }
 }
-typedef ImGuiInputTextCallback      ImGuiTextEditCallback;    // OBSOLETE in 1.63 (from Aug 2018): made the names consistent
+typedef ImGuiInputTextCallback      ImGuiTextEditCallback;    // OBSOLETED in 1.63 (from Aug 2018): made the names consistent
 typedef ImGuiInputTextCallbackData  ImGuiTextEditCallbackData;
 #endif
 
@@ -2247,7 +2247,7 @@ struct ImFontAtlas
     int                         CustomRectIds[1];   // Identifiers of custom texture rectangle used by ImFontAtlas/ImDrawList
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    typedef ImFontGlyphRangesBuilder GlyphRangesBuilder; // OBSOLETE 1.67+
+    typedef ImFontGlyphRangesBuilder GlyphRangesBuilder; // OBSOLETED in 1.67+
 #endif
 };
 
@@ -2301,7 +2301,7 @@ struct ImFont
     IMGUI_API void              SetFallbackChar(ImWchar c);
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
-    typedef ImFontGlyph Glyph; // OBSOLETE 1.52+
+    typedef ImFontGlyph Glyph; // OBSOLETED in 1.52+
 #endif
 };
 

imgui_demo.cpp

@@ -17,9 +17,18 @@
 // In this demo code, we frequently we use 'static' variables inside functions. A static variable persist across calls, so it is
 // essentially like a global variable but declared inside the scope of the function. We do this as a way to gather code and data
 // in the same place, to make the demo source code faster to read, faster to write, and smaller in size.
-// It also happens to be a convenient way of storing simple UI related information as long as your function doesn't need to be reentrant
-// or used in threads. This might be a pattern you will want to use in your code, but most of the real data you would be editing is
-// likely going to be stored outside your functions.
+// It also happens to be a convenient way of storing simple UI related information as long as your function doesn't need to be 
+// reentrant or used in multiple threads. This might be a pattern you will want to use in your code, but most of the real data
+// you would be editing is likely going to be stored outside your functions.
+
+// The Demo code is this file is designed to be easy to copy-and-paste in into your application!
+// Because of this:
+// - We never omit the ImGui:: namespace when calling functions, even though most of our code is already in the same namespace.
+// - We try to declare static variables in the local scope, as close as possible to the code using them.
+// - We never use any of the helpers/facilities used internally by dear imgui, unless it has been exposed in the public API (imgui.h).
+// - We never use maths operators on ImVec2/ImVec4. For other imgui sources files, they are provided by imgui_internal.h w/ IMGUI_DEFINE_MATH_OPERATORS,
+//   for your own sources file they are optional and require you either enable those, either provide your own via IM_VEC2_CLASS_EXTRA in imconfig.h.
+//   Because we don't want to assume anything about your support of maths operators, we don't use them in imgui_demo.cpp.
 
 /*
 
@@ -2108,14 +2117,21 @@ static void ShowDemoWindowLayout()
         HelpMarker("Use SetScrollHereY() or SetScrollFromPosY() to scroll to a given position.");
 
         static bool track = true;
-        static int track_line = 50, scroll_to_px = 200;
+        static int track_line = 50;
+        static float scroll_to_off_px = 0.0f;
+        static float scroll_to_pos_px = 200.0f;
         ImGui::Checkbox("Track", &track);
         ImGui::PushItemWidth(100);
-        ImGui::SameLine(130); track |= ImGui::DragInt("##line", &track_line, 0.25f, 0, 99, "Line = %d");
-        bool scroll_to = ImGui::Button("Scroll To Pos");
-        ImGui::SameLine(130); scroll_to |= ImGui::DragInt("##pos_y", &scroll_to_px, 1.00f, 0, 9999, "Y = %d px");
+        ImGui::SameLine(140); track |= ImGui::DragInt("##line", &track_line, 0.25f, 0, 99, "Line = %d");
+
+        bool scroll_to_off = ImGui::Button("Scroll Offset");
+        ImGui::SameLine(140); scroll_to_off |= ImGui::DragFloat("##off_y", &scroll_to_off_px, 1.00f, 0, 9999, "+%.0f px");
+
+        bool scroll_to_pos = ImGui::Button("Scroll To Pos");
+        ImGui::SameLine(140); scroll_to_pos |= ImGui::DragFloat("##pos_y", &scroll_to_pos_px, 1.00f, 0, 9999, "Y = %.0f px");
+
         ImGui::PopItemWidth();
-        if (scroll_to) 
+        if (scroll_to_off || scroll_to_pos)
             track = false;
 
         ImGuiStyle& style = ImGui::GetStyle();
@@ -2125,9 +2141,13 @@ static void ShowDemoWindowLayout()
             if (i > 0) ImGui::SameLine();
             ImGui::BeginGroup();
             ImGui::Text("%s", i == 0 ? "Top" : i == 1 ? "25%" : i == 2 ? "Center" : i == 3 ? "75%" : "Bottom");
-            ImGui::BeginChild(ImGui::GetID((void*)(intptr_t)i), ImVec2(child_w, 200.0f), true);
-            if (scroll_to)
-                ImGui::SetScrollFromPosY(ImGui::GetCursorStartPos().y + scroll_to_px, i * 0.25f);
+
+            ImGuiWindowFlags child_flags = ImGuiWindowFlags_MenuBar;
+            ImGui::BeginChild(ImGui::GetID((void*)(intptr_t)i), ImVec2(child_w, 200.0f), true, child_flags);
+            if (scroll_to_off)
+                ImGui::SetScrollY(scroll_to_off_px);
+            if (scroll_to_pos)
+                ImGui::SetScrollFromPosY(ImGui::GetCursorStartPos().y + scroll_to_pos_px, i * 0.25f);
             for (int line = 0; line < 100; line++)
             {
                 if (track && line == track_line)
@@ -2143,7 +2163,7 @@ static void ShowDemoWindowLayout()
             float scroll_y = ImGui::GetScrollY();
             float scroll_max_y = ImGui::GetScrollMaxY();
             ImGui::EndChild();
-            ImGui::Text("%.0f/%0.f", scroll_y, scroll_max_y);
+            ImGui::Text("%.0f/%.0f", scroll_y, scroll_max_y);
             ImGui::EndGroup();
         }
         ImGui::TreePop();
@@ -2193,6 +2213,97 @@ static void ShowDemoWindowLayout()
             ImGui::SetScrollX(ImGui::GetScrollX() + scroll_x_delta);
             ImGui::EndChild();
         }
+        ImGui::Spacing();
+
+        static bool show_horizontal_contents_size_demo_window = false;
+        ImGui::Checkbox("Show Horizontal contents size demo window", &show_horizontal_contents_size_demo_window);
+
+        if (show_horizontal_contents_size_demo_window)
+        {
+            static bool show_h_scrollbar = true;
+            static bool show_button = true;
+            static bool show_tree_nodes = true;
+            static bool show_text_wrapped = false;
+            static bool show_columns = true;
+            static bool show_tab_bar = true;
+            static bool show_child = false;
+            static bool explicit_content_size = false;
+            static float contents_size_x = 300.0f;
+            if (explicit_content_size)
+                ImGui::SetNextWindowContentSize(ImVec2(contents_size_x, 0.0f));
+            ImGui::Begin("Horizontal contents size demo window", &show_horizontal_contents_size_demo_window, show_h_scrollbar ? ImGuiWindowFlags_HorizontalScrollbar : 0);
+            ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(2, 0));
+            ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(2, 0));
+            HelpMarker("Test of different widgets react and impact the work rectangle growing when horizontal scrolling is enabled.\n\nUse 'Metrics->Tools->Show windows rectangles' to visualize rectangles.");
+            ImGui::Checkbox("H-scrollbar", &show_h_scrollbar);
+            ImGui::Checkbox("Button", &show_button);            // Will grow contents size (unless explicitly overwritten)
+            ImGui::Checkbox("Tree nodes", &show_tree_nodes);    // Will grow contents size and display highlight over full width
+            ImGui::Checkbox("Text wrapped", &show_text_wrapped);// Will grow and use contents size
+            ImGui::Checkbox("Columns", &show_columns);          // Will use contents size
+            ImGui::Checkbox("Tab bar", &show_tab_bar);          // Will use contents size
+            ImGui::Checkbox("Child", &show_child);              // Will grow and use contents size
+            ImGui::Checkbox("Explicit content size", &explicit_content_size);
+            ImGui::Text("Scroll %.1f/%.1f %.1f/%.1f", ImGui::GetScrollX(), ImGui::GetScrollMaxX(), ImGui::GetScrollY(), ImGui::GetScrollMaxY());
+            if (explicit_content_size)
+            {
+                ImGui::SameLine();
+                ImGui::SetNextItemWidth(100);
+                ImGui::DragFloat("##csx", &contents_size_x);
+                ImVec2 p = ImGui::GetCursorScreenPos(); 
+                ImGui::GetWindowDrawList()->AddRectFilled(p, ImVec2(p.x + 10, p.y + 10), IM_COL32_WHITE);
+                ImGui::GetWindowDrawList()->AddRectFilled(ImVec2(p.x + contents_size_x - 10, p.y), ImVec2(p.x + contents_size_x, p.y + 10), IM_COL32_WHITE);
+                ImGui::Dummy(ImVec2(0, 10));
+            }
+            ImGui::PopStyleVar(2);
+            ImGui::Separator();
+            if (show_button)
+            {
+                ImGui::Button("this is a 300-wide button", ImVec2(300, 0));
+            }
+            if (show_tree_nodes)
+            {
+                bool open = true;
+                if (ImGui::TreeNode("this is a tree node"))
+                {
+                    if (ImGui::TreeNode("another one of those tree node..."))
+                    {
+                        ImGui::Text("Some tree contents");
+                        ImGui::TreePop();
+                    }
+                    ImGui::TreePop();
+                }
+                ImGui::CollapsingHeader("CollapsingHeader", &open);
+            }
+            if (show_text_wrapped)
+            {
+                ImGui::TextWrapped("This text should automatically wrap on the edge of the work rectangle.");
+            }
+            if (show_columns)
+            {
+                ImGui::Columns(4);
+                for (int n = 0; n < 4; n++)
+                {
+                    ImGui::Text("Width %.2f", ImGui::GetColumnWidth());
+                    ImGui::NextColumn();
+                }
+                ImGui::Columns(1);
+            }
+            if (show_tab_bar && ImGui::BeginTabBar("Hello"))
+            {
+                if (ImGui::BeginTabItem("OneOneOne")) { ImGui::EndTabItem(); }
+                if (ImGui::BeginTabItem("TwoTwoTwo")) { ImGui::EndTabItem(); }
+                if (ImGui::BeginTabItem("ThreeThreeThree")) { ImGui::EndTabItem(); }
+                if (ImGui::BeginTabItem("FourFourFour")) { ImGui::EndTabItem(); }
+                ImGui::EndTabBar();
+            }
+            if (show_child)
+            {
+                ImGui::BeginChild("child", ImVec2(0,0), true);
+                ImGui::EndChild();
+            }
+            ImGui::End();
+        }
+
         ImGui::TreePop();
     }
 

imgui_internal.h

@@ -1327,7 +1327,7 @@ struct IMGUI_API ImGuiWindowTempData
     ImVec2                  CursorPos;
     ImVec2                  CursorPosPrevLine;
     ImVec2                  CursorStartPos;         // Initial position in client area with padding
-    ImVec2                  CursorMaxPos;           // Used to implicitly calculate the size of our contents, always growing during the frame. Turned into window->SizeContents at the beginning of next frame
+    ImVec2                  CursorMaxPos;           // Used to implicitly calculate the size of our contents, always growing during the frame. Used to calculate window->ContentSize at the beginning of next frame
     ImVec2                  CurrLineSize;
     ImVec2                  PrevLineSize;
     float                   CurrLineTextBaseOffset;
@@ -1415,9 +1415,8 @@ struct IMGUI_API ImGuiWindow
     ImVec2                  Pos;                                // Position (always rounded-up to nearest pixel)
     ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
     ImVec2                  SizeFull;                           // Size when non collapsed
-    ImVec2                  SizeFullAtLastBegin;                // Copy of SizeFull at the end of Begin. This is the reference value we'll use on the next frame to decide if we need scrollbars.
-    ImVec2                  SizeContents;                       // Size of contents (== extents reach of the drawing cursor) from previous frame. FIXME: Include decoration, window title, border, menu, etc. Ideally should remove them from this value?
-    ImVec2                  SizeContentsExplicit;               // Size of contents explicitly set by the user via SetNextWindowContentSize(). EXCLUDE decorations. Making this not consistent with the above!
+    ImVec2                  ContentSize;                        // Size of contents/scrollable client area (calculated from the extents reach of the cursor) from previous frame. Does not include window decoration or window padding.
+    ImVec2                  ContentSizeExplicit;                // Size of contents/scrollable client area explicitly request by the user via SetNextWindowContentSize().
     ImVec2                  WindowPadding;                      // Window padding at the time of begin.
     float                   WindowRounding;                     // Window rounding at the time of begin.
     float                   WindowBorderSize;                   // Window border size at the time of begin.
@@ -1425,6 +1424,7 @@ struct IMGUI_API ImGuiWindow
     ImGuiID                 MoveId;                             // == window->GetID("#MOVE")
     ImGuiID                 ChildId;                            // ID of corresponding item in parent window (for navigation to return from child window to parent window)
     ImVec2                  Scroll;
+    ImVec2                  ScrollMax;
     ImVec2                  ScrollTarget;                       // target scroll position. stored as cursor position with scrolling canceled out, so the highest point is always 0.0f. (FLT_MAX for no change)
     ImVec2                  ScrollTargetCenterRatio;            // 0.0f = scroll so that target position is at top, 0.5f = scroll so that target position is centered
     ImVec2                  ScrollbarSizes;                     // Size taken by scrollbars on each axis
@@ -1459,13 +1459,17 @@ struct IMGUI_API ImGuiWindow
 
     ImGuiWindowTempData     DC;                                 // Temporary per-window data, reset at the beginning of the frame. This used to be called ImGuiDrawContext, hence the "DC" variable name.
     ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack
-    ImRect                  ClipRect;                           // Current clipping rectangle. = DrawList->clip_rect_stack.back(). Scissoring / clipping rectangle. x1, y1, x2, y2.
-    ImRect                  OuterRectClipped;                   // == WindowRect just after setup in Begin(). == window->Rect() for root window.
-    ImRect                  InnerRect;                          // Inner rectangle
-    ImRect                  InnerClipRect;                      // == InnerRect minus WindowPadding.x, clipped within viewport or parent clip rect.
-    ImRect                  WorkRect;                           // == InnerRect minus WindowPadding.x
-    ImRect                  ContentsRegionRect;                 // FIXME: This is currently confusing/misleading. Maximum visible content position ~~ Pos + (SizeContentsExplicit ? SizeContentsExplicit : Size - ScrollbarSizes) - CursorStartPos, per axis
+
+    // The best way to understand what those rectangles are is to use the 'Metrics -> Tools -> Show windows rectangles' viewer.
+    // The main 'OuterRect', omitted as a field, is window->Rect().
+    ImRect                  OuterRectClipped;                   // == Window->Rect() just after setup in Begin(). == window->Rect() for root window.
+    ImRect                  InnerRect;                          // Inner rectangle (omit title bar, menu bar)
+    ImRect                  InnerClipRect;                      // == InnerRect shrunk by WindowPadding*0.5f on each side, clipped within viewport or parent clip rect.
+    ImRect                  WorkRect;                           // Cover the whole scrolling region, shrunk by WindowPadding*1.0f on each side. This is meant to replace ContentsRegionRect over time (from 1.71+ onward).
+    ImRect                  ClipRect;                           // Current clipping/scissoring rectangle, evolve as we are using PushClipRect(), etc. == DrawList->clip_rect_stack.back().
+    ImRect                  ContentsRegionRect;                 // FIXME: This is currently confusing/misleading. It is essentially WorkRect but not handling of scrolling. We currently rely on it as right/bottom aligned sizing operation need some size to rely on.
     ImVec2ih                HitTestHoleSize, HitTestHoleOffset;
+
     int                     LastFrameActive;                    // Last frame number the window was Active.
     int                     LastFrameJustFocused;               // Last frame number the window was made Focused.
     float                   ItemWidthDefault;
@@ -1631,8 +1635,6 @@ namespace ImGui
     IMGUI_API bool          IsWindowNavFocusable(ImGuiWindow* window);
     IMGUI_API void          SetWindowScrollX(ImGuiWindow* window, float new_scroll_x);
     IMGUI_API void          SetWindowScrollY(ImGuiWindow* window, float new_scroll_y);
-    IMGUI_API float         GetWindowScrollMaxX(ImGuiWindow* window);
-    IMGUI_API float         GetWindowScrollMaxY(ImGuiWindow* window);
     IMGUI_API ImRect        GetWindowAllowedExtentRect(ImGuiWindow* window);
     IMGUI_API void          SetWindowPos(ImGuiWindow* window, const ImVec2& pos, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowSize(ImGuiWindow* window, const ImVec2& size, ImGuiCond cond = 0);

imgui_widgets.cpp

@@ -878,7 +878,7 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, floa
         }
 
         // Apply scroll
-        // It is ok to modify Scroll here because we are being called in Begin() after the calculation of SizeContents and before setting up our starting position
+        // It is ok to modify Scroll here because we are being called in Begin() after the calculation of ContentSize and before setting up our starting position
         const float scroll_v_norm = ImSaturate((clicked_v_norm - g.ScrollbarClickDeltaToGrabCenter - grab_h_norm * 0.5f) / (1.0f - grab_h_norm));
         *p_scroll_v = (float)(int)(0.5f + scroll_v_norm * scroll_max);//(win_size_contents_v - win_size_v));
 
@@ -914,22 +914,26 @@ void ImGui::Scrollbar(ImGuiAxis axis)
 
     // Calculate scrollbar bounding box
     const ImRect outer_rect = window->Rect();
+    const ImRect inner_rect = window->InnerRect;
+    const float border_size = window->WindowBorderSize;
+    const float scrollbar_size = window->ScrollbarSizes[axis ^ 1];
+    IM_ASSERT(scrollbar_size > 0.0f);
     const float other_scrollbar_size = window->ScrollbarSizes[axis];
     ImDrawCornerFlags rounding_corners = (other_scrollbar_size <= 0.0f) ? ImDrawCornerFlags_BotRight : 0;
     ImRect bb;
     if (axis == ImGuiAxis_X)
     {
-        bb.Min = ImVec2(window->InnerRect.Min.x, window->InnerRect.Max.y);
-        bb.Max = ImVec2(window->InnerRect.Max.x, outer_rect.Max.y - window->WindowBorderSize);
+        bb.Min = ImVec2(inner_rect.Min.x, outer_rect.Max.y - border_size - scrollbar_size);
+        bb.Max = ImVec2(inner_rect.Max.x, outer_rect.Max.y);
         rounding_corners |= ImDrawCornerFlags_BotLeft;
     }
     else
     {
-        bb.Min = ImVec2(window->InnerRect.Max.x, window->InnerRect.Min.y);
-        bb.Max = ImVec2(outer_rect.Max.x - window->WindowBorderSize, window->InnerRect.Max.y);
+        bb.Min = ImVec2(outer_rect.Max.x - border_size - scrollbar_size, inner_rect.Min.y);
+        bb.Max = ImVec2(outer_rect.Max.x, window->InnerRect.Max.y);
         rounding_corners |= ((window->Flags & ImGuiWindowFlags_NoTitleBar) && !(window->Flags & ImGuiWindowFlags_MenuBar)) ? ImDrawCornerFlags_TopRight : 0;
     }
-    ScrollbarEx(bb, id, axis, &window->Scroll[axis], window->SizeFull[axis] - other_scrollbar_size, window->SizeContents[axis], rounding_corners);
+    ScrollbarEx(bb, id, axis, &window->Scroll[axis], inner_rect.Max[axis] - inner_rect.Min[axis], window->ContentSize[axis] + window->WindowPadding[axis] * 2.0f, rounding_corners);
 }
 
 void ImGui::Image(ImTextureID user_texture_id, const ImVec2& size, const ImVec2& uv0, const ImVec2& uv1, const ImVec4& tint_col, const ImVec4& border_col)
@@ -5161,12 +5165,12 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
     // We vertically grow up to current line height up the typical widget height.
     const float text_base_offset_y = ImMax(padding.y, window->DC.CurrLineTextBaseOffset); // Latch before ItemSize changes it
     const float frame_height = ImMax(ImMin(window->DC.CurrLineSize.y, g.FontSize + style.FramePadding.y*2), label_size.y + padding.y*2);
-    ImRect frame_bb = ImRect(window->DC.CursorPos, ImVec2(GetContentRegionMaxAbs().x, window->DC.CursorPos.y + frame_height));
+    ImRect frame_bb = ImRect(window->DC.CursorPos, ImVec2(window->WorkRect.Max.x, window->DC.CursorPos.y + frame_height));
     if (display_frame)
     {
         // Framed header expand a little outside the default padding
-        frame_bb.Min.x -= (float)(int)(window->WindowPadding.x * 0.5f) - 1;
-        frame_bb.Max.x += (float)(int)(window->WindowPadding.x * 0.5f) - 1;
+        frame_bb.Min.x -= (float)(int)(window->WindowPadding.x * 0.5f - 1.0f);
+        frame_bb.Max.x += (float)(int)(window->WindowPadding.x * 0.5f - 1.0f);
     }
 
     const float text_offset_x = (g.FontSize + (display_frame ? padding.x*3 : padding.x*2));   // Collapser arrow width + Spacing
@@ -6360,7 +6364,7 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     tab_bar->FramePadding = g.Style.FramePadding;
 
     // Layout
-    ItemSize(ImVec2(tab_bar->OffsetMax, tab_bar->BarRect.GetHeight()));
+    ItemSize(ImVec2(0.0f /*tab_bar->OffsetMax*/, tab_bar->BarRect.GetHeight())); // Don't feed width back
     window->DC.CursorPos.x = tab_bar->BarRect.Min.x;
 
     // Draw separator
@@ -6374,8 +6378,8 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     }
     else
     {
-        const float separator_min_x = tab_bar->BarRect.Min.x - window->WindowPadding.x;
-        const float separator_max_x = tab_bar->BarRect.Max.x + window->WindowPadding.x;
+        const float separator_min_x = tab_bar->BarRect.Min.x - ImFloor(window->WindowPadding.x * 0.5f);
+        const float separator_max_x = tab_bar->BarRect.Max.x + ImFloor(window->WindowPadding.x * 0.5f);
         window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
     }
     return true;
@@ -6504,7 +6508,8 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
     }
 
     // Compute width
-    const float width_avail = tab_bar->BarRect.GetWidth();
+    const float initial_offset_x = 0.0f; // g.Style.ItemInnerSpacing.x;
+    const float width_avail = ImMax(tab_bar->BarRect.GetWidth() - initial_offset_x, 0.0f);
     float width_excess = (width_avail < width_total_contents) ? (width_total_contents - width_avail) : 0.0f;
     if (width_excess > 0.0f && (tab_bar->Flags & ImGuiTabBarFlags_FittingPolicyResizeDown))
     {
@@ -6524,7 +6529,8 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
     }
 
     // Layout all active tabs
-    float offset_x = 0.0f;
+    float offset_x = initial_offset_x;
+    tab_bar->OffsetNextTab = offset_x; // This is used by non-reorderable tab bar where the submission order is always honored.
     for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
     {
         ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
@@ -6534,7 +6540,6 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         offset_x += tab->Width + g.Style.ItemInnerSpacing.x;
     }
     tab_bar->OffsetMax = ImMax(offset_x - g.Style.ItemInnerSpacing.x, 0.0f);
-    tab_bar->OffsetNextTab = 0.0f;
 
     // Horizontal scrolling buttons
     const bool scrolling_buttons = (tab_bar->OffsetMax > tab_bar->BarRect.GetWidth() && tab_bar->Tabs.Size > 1) && !(tab_bar->Flags & ImGuiTabBarFlags_NoTabListScrollingButtons) && (tab_bar->Flags & ImGuiTabBarFlags_FittingPolicyScroll);
@@ -6962,7 +6967,10 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     if (want_clip_rect)
         PushClipRect(ImVec2(ImMax(bb.Min.x, tab_bar->BarRect.Min.x), bb.Min.y - 1), ImVec2(tab_bar->BarRect.Max.x, bb.Max.y), true);
 
-    ItemSize(bb, style.FramePadding.y);
+    ImVec2 backup_cursor_max_pos = window->DC.CursorMaxPos;
+    ItemSize(bb.GetSize(), style.FramePadding.y);
+    window->DC.CursorMaxPos = backup_cursor_max_pos;
+
     if (!ItemAdd(bb, id))
     {
         if (want_clip_rect)