Windows: fixed double-click collapse toggle not owning the mouse button. (#9439)

docs/CHANGELOG.txt

@@ -52,6 +52,9 @@ Other Changes:
     for user code to bypass it without using a clickable item. (#9382)
   - Clicking on a window's empty-space to move/focus a window checks
     for lack of queued focus request. (#9382)
+  - Fixed double-click collapse toggle not owning the mouse button. If a
+    `SetNextWindowPos()` with pivot was queued in the same frame, the second
+    click could trigger another item in the same window. (#9439) [@Cleroth]
 - InputText:
   - Added `style.InputTextCursorSize` to configure cursor/caret thickness. (#7031, #9409)
     This is automatically scaled by `style.ScaleAllSizes()`.

imgui.cpp

@@ -7714,7 +7714,10 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             ImRect title_bar_rect = window->TitleBarRect();
             if (g.HoveredWindow == window && g.HoveredId == 0 && g.HoveredIdPreviousFrame == 0 && g.ActiveId == 0 && IsMouseHoveringRect(title_bar_rect.Min, title_bar_rect.Max))
                 if (g.IO.MouseClickedCount[0] == 2 && GetKeyOwner(ImGuiKey_MouseLeft) == ImGuiKeyOwner_NoOwner)
+                {
                     window->WantCollapseToggle = true;
+                    SetKeyOwner(ImGuiKey_MouseLeft, window->MoveId); // Claim input the same way ButtonBehavior() does. Prevent a same-frame move from triggering other items. (#9439)
+                }
             if (window->WantCollapseToggle)
             {
                 window->Collapsed = !window->Collapsed;