Combo: Fixed not reusing windows optimally when used inside a popup stack.

docs/CHANGELOG.txt

@@ -66,6 +66,7 @@ Other changes:
   the effect would be very disastrous in term of confusion, as reopening would steal focus).
 - Popups: Slight change to popup closing logic (e.g. after focusing another window) which skipped
   over popups that are also child windows.
+- Combo: Fixed not reusing windows optimally when used inside a popup stack.
 - Debug Tools: Metrics: Fixed debug break in SetShortcutRouting() not handling ImGuiMod_Shortcut redirect.
 - Debug Tools: Debug Log: Added "Input Routing" logging.
 - Debug Tools: Added "nop" to IM_DEBUG_BREAK macro on GCC to work around GDB bug (#7266) [@Peter0x44]

imgui.cpp

@@ -6434,7 +6434,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     window_stack_data.StackSizesOnBegin.SetToContextState(&g);
     g.CurrentWindowStack.push_back(window_stack_data);
     if (flags & ImGuiWindowFlags_ChildMenu)
-        g.BeginMenuCount++;
+        g.BeginMenuDepth++;
 
     // Update ->RootWindow and others pointers (before any possible call to FocusWindow)
     if (first_begin_of_the_frame)
@@ -7106,7 +7106,7 @@ void ImGui::End()
     // Pop from window stack
     g.LastItemData = g.CurrentWindowStack.back().ParentLastItemDataBackup;
     if (window->Flags & ImGuiWindowFlags_ChildMenu)
-        g.BeginMenuCount--;
+        g.BeginMenuDepth--;
     if (window->Flags & ImGuiWindowFlags_Popup)
         g.BeginPopupStack.pop_back();
     g.CurrentWindowStack.back().StackSizesOnBegin.CompareWithContextState(&g);
@@ -10926,7 +10926,7 @@ bool ImGui::BeginPopupEx(ImGuiID id, ImGuiWindowFlags flags)
 
     char name[20];
     if (flags & ImGuiWindowFlags_ChildMenu)
-        ImFormatString(name, IM_ARRAYSIZE(name), "##Menu_%02d", g.BeginMenuCount); // Recycle windows based on depth
+        ImFormatString(name, IM_ARRAYSIZE(name), "##Menu_%02d", g.BeginMenuDepth); // Recycle windows based on depth
     else
         ImFormatString(name, IM_ARRAYSIZE(name), "##Popup_%08x", id); // Not recycling, so we can close/open during the same frame
 

imgui_internal.h

@@ -2028,8 +2028,6 @@ struct ImGuiContext
     ImVector<ImGuiPopupData>        BeginPopupStack;            // Which level of BeginPopup() we are in (reset every frame)
     ImVector<ImGuiNavTreeNodeData>  NavTreeNodeStack;           // Stack for TreeNode() when a NavLeft requested is emitted.
 
-    int                     BeginMenuCount;
-
     // Viewports
     ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (Size==1 in 'master' branch). Each viewports hold their copy of ImDrawData.
 
@@ -2154,6 +2152,8 @@ struct ImGuiContext
     ImGuiInputTextDeactivatedState InputTextDeactivatedState;
     ImFont                  InputTextPasswordFont;
     ImGuiID                 TempInputId;                        // Temporary text input when CTRL+clicking on a slider, etc.
+    int                     BeginMenuDepth;
+    int                     BeginComboDepth;
     ImGuiColorEditFlags     ColorEditOptions;                   // Store user options for color edit widgets
     ImGuiID                 ColorEditCurrentID;                 // Set temporarily while inside of the parent-most ColorEdit4/ColorPicker4 (because they call each others).
     ImGuiID                 ColorEditSavedID;                   // ID we are saving/restoring HS for
@@ -2307,7 +2307,6 @@ struct ImGuiContext
         CurrentFocusScopeId = 0;
         CurrentItemFlags = ImGuiItemFlags_None;
         DebugShowGroupRects = false;
-        BeginMenuCount = 0;
 
         NavWindow = NULL;
         NavId = NavFocusScopeId = NavActivateId = NavActivateDownId = NavActivatePressedId = 0;
@@ -2371,6 +2370,7 @@ struct ImGuiContext
         MouseStationaryTimer = 0.0f;
 
         TempInputId = 0;
+        BeginMenuDepth = BeginComboDepth = 0;
         ColorEditOptions = ImGuiColorEditFlags_DefaultOptions_;
         ColorEditCurrentID = ColorEditSavedID = 0;
         ColorEditSavedHue = ColorEditSavedSat = 0.0f;

imgui_widgets.cpp

@@ -1784,7 +1784,7 @@ bool ImGui::BeginComboPopup(ImGuiID popup_id, const ImRect& bb, ImGuiComboFlags
 
     // This is essentially a specialized version of BeginPopupEx()
     char name[16];
-    ImFormatString(name, IM_ARRAYSIZE(name), "##Combo_%02d", g.BeginPopupStack.Size); // Recycle windows based on depth
+    ImFormatString(name, IM_ARRAYSIZE(name), "##Combo_%02d", g.BeginComboDepth); // Recycle windows based on depth
 
     // Set position given a custom constraint (peak into expected window size so we can position it)
     // FIXME: This might be easier to express with an hypothetical SetNextWindowPosConstraints() function?
@@ -1811,12 +1811,15 @@ bool ImGui::BeginComboPopup(ImGuiID popup_id, const ImRect& bb, ImGuiComboFlags
         IM_ASSERT(0);   // This should never happen as we tested for IsPopupOpen() above
         return false;
     }
+    g.BeginComboDepth++;
     return true;
 }
 
 void ImGui::EndCombo()
 {
+    ImGuiContext& g = *GImGui;
     EndPopup();
+    g.BeginComboDepth--;
 }
 
 // Call directly after the BeginCombo/EndCombo block. The preview is designed to only host non-interactive elements