Fixed ImGuiWindowFlags_UnsavedDocument clipping label in docked windows with no close button. (#5745)

+ TabBar: starts displaying the unsaved document marker with a frame delay to match how close button is processed, otherwise the transition would be noticeable.

imgui_internal.h

@@ -2829,7 +2829,7 @@ namespace ImGui
     IMGUI_API void          TabBarQueueReorderFromMousePos(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, ImVec2 mouse_pos);
     IMGUI_API bool          TabBarProcessReorder(ImGuiTabBar* tab_bar);
     IMGUI_API bool          TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags);
-    IMGUI_API ImVec2        TabItemCalcSize(const char* label, bool has_close_button);
+    IMGUI_API ImVec2        TabItemCalcSize(const char* label, bool has_close_button_or_unsaved_marker);
     IMGUI_API void          TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImU32 col);
     IMGUI_API void          TabItemLabelAndCloseButton(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImVec2 frame_padding, const char* label, ImGuiID tab_id, ImGuiID close_button_id, bool is_contents_visible, bool* out_just_closed, bool* out_text_clipped);
 

imgui_widgets.cpp

@@ -7577,8 +7577,8 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         // Additionally, when using TabBarAddTab() to manipulate tab bar order we occasionally insert new tabs that don't have a width yet,
         // and we cannot wait for the next BeginTabItem() call. We cannot compute this width within TabBarAddTab() because font size depends on the active window.
         const char* tab_name = tab_bar->GetTabName(tab);
-        const bool has_close_button = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) ? false : true;
-        tab->ContentWidth = (tab->RequestedWidth >= 0.0f) ? tab->RequestedWidth : TabItemCalcSize(tab_name, has_close_button).x;
+        const bool has_close_button_or_unsaved_marker = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) == 0 || (tab->Flags & ImGuiTabItemFlags_UnsavedDocument);
+        tab->ContentWidth = (tab->RequestedWidth >= 0.0f) ? tab->RequestedWidth : TabItemCalcSize(tab_name, has_close_button_or_unsaved_marker).x;
 
         int section_n = TabItemGetSectionIdx(tab);
         ImGuiTabBarSection* section = &sections[section_n];
@@ -8105,7 +8105,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     tab_bar->LastTabItemIdx = (ImS16)tab_bar->Tabs.index_from_ptr(tab);
 
     // Calculate tab contents size
-    ImVec2 size = TabItemCalcSize(label, p_open != NULL);
+    ImVec2 size = TabItemCalcSize(label, (p_open != NULL) || (flags & ImGuiTabItemFlags_UnsavedDocument));
     tab->RequestedWidth = -1.0f;
     if (g.NextItemData.Flags & ImGuiNextItemDataFlags_HasWidth)
         size.x = tab->RequestedWidth = g.NextItemData.Width;
@@ -8117,6 +8117,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     const bool tab_bar_appearing = (tab_bar->PrevFrameVisible + 1 < g.FrameCount);
     const bool tab_bar_focused = (tab_bar->Flags & ImGuiTabBarFlags_IsFocused) != 0;
     const bool tab_appearing = (tab->LastFrameVisible + 1 < g.FrameCount);
+    const bool tab_just_unsaved = (flags & ImGuiTabItemFlags_UnsavedDocument) && !(tab->Flags & ImGuiTabItemFlags_UnsavedDocument);
     const bool is_tab_button = (flags & ImGuiTabItemFlags_Button) != 0;
     tab->LastFrameVisible = g.FrameCount;
     tab->Flags = flags;
@@ -8248,7 +8249,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     const ImGuiID close_button_id = p_open ? GetIDWithSeed("#CLOSE", NULL, id) : 0;
     bool just_closed;
     bool text_clipped;
-    TabItemLabelAndCloseButton(display_draw_list, bb, flags, tab_bar->FramePadding, label, id, close_button_id, tab_contents_visible, &just_closed, &text_clipped);
+    TabItemLabelAndCloseButton(display_draw_list, bb, tab_just_unsaved ? (flags & ~ImGuiTabItemFlags_UnsavedDocument) : flags, tab_bar->FramePadding, label, id, close_button_id, tab_contents_visible, &just_closed, &text_clipped);
     if (just_closed && p_open != NULL)
     {
         *p_open = false;
@@ -8292,12 +8293,12 @@ void    ImGui::SetTabItemClosed(const char* label)
     }
 }
 
-ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button)
+ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button_or_unsaved_marker)
 {
     ImGuiContext& g = *GImGui;
     ImVec2 label_size = CalcTextSize(label, NULL, true);
     ImVec2 size = ImVec2(label_size.x + g.Style.FramePadding.x, label_size.y + g.Style.FramePadding.y * 2.0f);
-    if (has_close_button)
+    if (has_close_button_or_unsaved_marker)
         size.x += g.Style.FramePadding.x + (g.Style.ItemInnerSpacing.x + g.FontSize); // We use Y intentionally to fit the close button circle.
     else
         size.x += g.Style.FramePadding.x + 1.0f;