Begin(): Tidying up some code, should be a no-op.

imgui.cpp

@@ -3965,19 +3965,20 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
     CheckStacksSize(window, true);
     IM_ASSERT(parent_window != NULL || !(flags & ImGuiWindowFlags_ChildWindow));
 
-    bool window_was_active = (window->LastFrameActive == current_frame - 1);   // Not using !WasActive because the implicit "Debug" window would always toggle off->on
+    // FIXME: This is currently true if we call Begin() multiple times in a row on a same window.
+    bool window_activated = (window->LastFrameActive != current_frame - 1);   // Not using !WasActive because the implicit "Debug" window would always toggle off->on
     if (flags & ImGuiWindowFlags_Popup)
     {
         ImGuiPopupRef& popup_ref = g.OpenPopupStack[g.CurrentPopupStack.Size];
-        window_was_active &= (window->PopupId == popup_ref.PopupId);
-        window_was_active &= (window == popup_ref.Window);
+        window_activated |= (window->PopupId != popup_ref.PopupId); // We recycle popups so treat window as activated if popup id changed
+        window_activated |= (window != popup_ref.Window);
         popup_ref.Window = window;
         g.CurrentPopupStack.push_back(popup_ref);
         window->PopupId = popup_ref.PopupId;
     }
 
     const bool window_appearing_after_being_hidden = (window->HiddenFrames == 1);
-    window->Appearing = (!window_was_active || window_appearing_after_being_hidden);
+    window->Appearing = (window_activated || window_appearing_after_being_hidden);
 
     // Process SetNextWindow***() calls
     bool window_pos_set_by_api = false, window_size_set_by_api = false;
@@ -4061,7 +4062,7 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
         else
             PushClipRect(fullscreen_rect.Min, fullscreen_rect.Max, true);
 
-        if (!window_was_active)
+        if (window_activated)
         {
             // Popup first latch mouse position, will position itself when it appears next frame
             window->AutoPosLastDirection = -1;
@@ -4095,7 +4096,7 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
         // Hide popup/tooltip window when first appearing while we measure size (because we recycle them)
         if (window->HiddenFrames > 0)
             window->HiddenFrames--;
-        if ((flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) != 0 && !window_was_active)
+        if ((flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) != 0 && window_activated)
         {
             window->HiddenFrames = 1;
             if (flags & ImGuiWindowFlags_AlwaysAutoResize)
@@ -4389,7 +4390,7 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
         window->DC.TreeDepth = 0;
         window->DC.StateStorage = &window->StateStorage;
         window->DC.GroupStack.resize(0);
-        window->MenuColumns.Update(3, style.ItemSpacing.x, !window_was_active);
+        window->MenuColumns.Update(3, style.ItemSpacing.x, window_activated);
 
         if (window->AutoFitFramesX > 0)
             window->AutoFitFramesX--;
@@ -4397,7 +4398,7 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
             window->AutoFitFramesY--;
 
         // New windows appears in front (we need to do that AFTER setting DC.CursorStartPos so our initial navigation reference rectangle can start around there)
-        if (!window_was_active && !(flags & ImGuiWindowFlags_NoFocusOnAppearing))
+        if (window_activated && !(flags & ImGuiWindowFlags_NoFocusOnAppearing))
             if (!(flags & (ImGuiWindowFlags_ChildWindow|ImGuiWindowFlags_Tooltip)) || (flags & ImGuiWindowFlags_Popup))
                 FocusWindow(window);