Allow restarting label editing in wxMSW multi-selection wxTreeCtrl

In a tree control with wxTR_MULTIPLE style, a click on the already
selected item doesn't start in-place editing if the control had lost
focus since the previous click, as such a click is supposed to just
restore the focus to the control and nothing else.

However the in-place editor itself takes the focus when it is shown,
so this flag remained set after the end of any label edit and the next
click on the item was silently swallowed instead of starting editing
it again, i.e. two clicks were needed to rename the item once more.

Don't set the flag when losing focus to our own editor then, but do
set it from the EN_KILLFOCUS handler if the editor loses focus to
another window, so that clicking back into the control still doesn't
start editing. Also check whether the editor is open in the mouse
click handler itself, as the click dismissing it shouldn't start a new
edit either, which used to be ensured by the same flag.

Assisted-by: Claude Opus 5

src/msw/treectrl.cpp

@@ -2853,6 +2853,14 @@ wxTreeCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
         HTREEITEM htOldItem = TreeView_GetSelection(GetHwnd());
         HTREEITEM htItem = TreeView_HitTest(GetHwnd(), &tvht);
 
+        // If a label is currently being edited, clicking in the tree just
+        // dismisses the editor and shouldn't do anything else, as it happens
+        // in the native control, but we have to check for this here because
+        // calling SetFocus() below ends the editing.
+        bool wasEditing = false;
+        if ( nMsg == WM_LBUTTONDOWN )
+            wasEditing = TreeView_GetEditControl(GetHwnd()) != nullptr;
+
         switch ( nMsg )
         {
             case WM_LBUTTONDOWN:
@@ -3034,8 +3042,9 @@ wxTreeCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
                         m_htClickedItem.Unset();
 
                         // prevent in-place editing from starting if focus lost
-                        // since previous click
-                        if ( m_focusLost )
+                        // since previous click or if this click just dismissed
+                        // the editor used for editing another label
+                        if ( m_focusLost || wasEditing )
                         {
                             ClearFocusedItem();
                             DoSelectItem(wxTreeItemId(htItem));
@@ -3278,7 +3287,16 @@ wxTreeCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
 
         if ( nMsg == WM_KILLFOCUS )
         {
-            m_focusLost = true;
+            // Losing the focus to our own in-place editor doesn't really
+            // count as losing it: if we did consider it lost here, the click
+            // on the selected item after the end of the label editing
+            // wouldn't start editing it again, as it should, because we would
+            // have taken it for a click just restoring the focus to the
+            // control (if the editor loses the focus to another window later,
+            // we do set the flag from the EN_KILLFOCUS handler below).
+            const HWND hwndEdit = TreeView_GetEditControl(GetHwnd());
+            if ( !hwndEdit || (HWND)wParam != hwndEdit )
+                m_focusLost = true;
         }
     }
     else if ( (nMsg == WM_KEYDOWN || nMsg == WM_SYSKEYDOWN) && isMultiple )
@@ -3328,6 +3346,12 @@ wxTreeCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
         {
             if ( m_textCtrl && m_textCtrl->GetHandle() == hwnd )
             {
+                // We don't set m_focusLost when giving the focus to the
+                // editor (see WM_KILLFOCUS handling above), so do it now if
+                // the focus goes to some other window and not back to us.
+                if ( ::GetFocus() != GetHwnd() )
+                    m_focusLost = true;
+
                 DoEndEditLabel();
 
                 processed = true;