refactor(editor): streamline ImGui card management across various editors

- Refactored multiple editor classes to ensure that ImGui::End() is always called after ImGui::Begin(), enhancing state management and preventing potential rendering issues.
- Updated the DungeonEditor, GraphicsEditor, ScreenEditor, MessageEditor, MusicEditor, and SpriteEditor to follow this pattern, improving code consistency and reliability.

Benefits:
- Improves the stability of the editor UI by ensuring proper handling of ImGui state.
- Enhances code readability and maintainability by standardizing the usage of ImGui functions across different editor components.

src/app/editor/dungeon/dungeon_editor_v2.cc

@@ -443,10 +443,7 @@ void DungeonEditorV2::DrawRoomsListCard() {
   if (selector_card.Begin()) {
     if (!rom_ || !rom_->is_loaded()) {
       ImGui::Text("ROM not loaded");
-      selector_card.End();
-      return;
-    }
-    
+    } else {
       // Add text filter
       static char room_filter[256] = "";
       ImGui::SetNextItemWidth(-1);
@@ -497,6 +494,7 @@ void DungeonEditorV2::DrawRoomsListCard() {
         ImGui::EndChild();
       }
     }
+  }
   selector_card.End();
 }
 
@@ -510,10 +508,7 @@ void DungeonEditorV2::DrawEntrancesListCard() {
   if (entrances_card.Begin()) {
     if (!rom_ || !rom_->is_loaded()) {
       ImGui::Text("ROM not loaded");
-      entrances_card.End();
-      return;
-    }
-    
+    } else {
       // Full entrance configuration UI (matching dungeon_room_selector layout)
       auto& current_entrance = entrances_[current_entrance_id_];
       
@@ -598,6 +593,7 @@ void DungeonEditorV2::DrawEntrancesListCard() {
         ImGui::EndChild();
       }
     }
+  }
   entrances_card.End();
 }
 
@@ -757,12 +753,8 @@ void DungeonEditorV2::DrawRoomGraphicsCard() {
   if (graphics_card.Begin()) {
     if (!rom_ || !rom_->is_loaded()) {
       ImGui::Text("ROM not loaded");
-      graphics_card.End();
-      return;
-    }
-    
+    } else if (current_room_id_ >= 0 && current_room_id_ < static_cast<int>(rooms_.size())) {
       // Show graphics for current room
-    if (current_room_id_ >= 0 && current_room_id_ < static_cast<int>(rooms_.size())) {
       auto& room = rooms_[current_room_id_];
       
       ImGui::Text("Room %03X Graphics", current_room_id_);

src/app/editor/graphics/graphics_editor.cc

@@ -112,28 +112,29 @@ absl::Status GraphicsEditor::Update() {
   prototype_card.SetDefaultSize(600, 500);
 
   // Get visibility flags from card manager and pass to Begin()
+  // Always call End() after Begin() - End() handles ImGui state safely
   if (sheet_editor_card.Begin(card_manager.GetVisibilityFlag("graphics.sheet_editor"))) {
     status_ = UpdateGfxEdit();
-    sheet_editor_card.End();
   }
+  sheet_editor_card.End();
 
   if (sheet_browser_card.Begin(card_manager.GetVisibilityFlag("graphics.sheet_browser"))) {
     if (asset_browser_.Initialized == false) {
       asset_browser_.Initialize(gfx::Arena::Get().gfx_sheets());
     }
     asset_browser_.Draw(gfx::Arena::Get().gfx_sheets());
-    sheet_browser_card.End();
   }
+  sheet_browser_card.End();
 
   if (player_anims_card.Begin(card_manager.GetVisibilityFlag("graphics.player_animations"))) {
     status_ = UpdateLinkGfxView();
-    player_anims_card.End();
   }
+  player_anims_card.End();
 
   if (prototype_card.Begin(card_manager.GetVisibilityFlag("graphics.prototype_viewer"))) {
     status_ = UpdateScadView();
-    prototype_card.End();
   }
+  prototype_card.End();
 
   CLEAR_AND_RETURN_STATUS(status_)
   return absl::OkStatus();

src/app/editor/graphics/screen_editor.cc

@@ -109,6 +109,7 @@ absl::Status ScreenEditor::Update() {
   naming_screen_card.SetDefaultSize(500, 400);
 
   // Get visibility flags from card manager and pass to Begin()
+  // Always call End() after Begin() - End() handles ImGui state safely
   if (dungeon_maps_card.Begin(card_manager.GetVisibilityFlag("screen.dungeon_maps"))) {
     DrawDungeonMapsEditor();
   }
@@ -116,7 +117,6 @@ absl::Status ScreenEditor::Update() {
   
   if (inventory_menu_card.Begin(card_manager.GetVisibilityFlag("screen.inventory_menu"))) {
     DrawInventoryMenuEditor();
-  
   }
   inventory_menu_card.End();
   
@@ -127,7 +127,6 @@ absl::Status ScreenEditor::Update() {
   
   if (title_screen_card.Begin(card_manager.GetVisibilityFlag("screen.title_screen"))) {
     DrawTitleScreenEditor();
-  
   }
   title_screen_card.End();
   

src/app/editor/message/message_editor.cc

@@ -151,8 +151,8 @@ absl::Status MessageEditor::Update() {
     list_card.SetDefaultSize(400, 600);
     if (list_card.Begin()) {
       DrawMessageList();
-      list_card.End();
     }
+    list_card.End();
   }
   
   // Message Editor Card
@@ -161,8 +161,8 @@ absl::Status MessageEditor::Update() {
     editor_card.SetDefaultSize(500, 600);
     if (editor_card.Begin()) {
       DrawCurrentMessage();
-      editor_card.End();
     }
+    editor_card.End();
   }
   
   // Font Atlas Card
@@ -172,8 +172,8 @@ absl::Status MessageEditor::Update() {
     if (font_card.Begin()) {
       DrawFontAtlas();
       DrawExpandedMessageSettings();
-      font_card.End();
     }
+    font_card.End();
   }
   
   // Dictionary Card
@@ -184,8 +184,8 @@ absl::Status MessageEditor::Update() {
       DrawTextCommands();
       DrawSpecialCharacters();
       DrawDictionary();
-      dict_card.End();
     }
+    dict_card.End();
   }
   
   return absl::OkStatus();

src/app/editor/music/music_editor.cc

@@ -48,20 +48,20 @@ absl::Status MusicEditor::Update() {
   // Music Tracker Card
   if (tracker_card.Begin(card_manager.GetVisibilityFlag("music.tracker"))) {
     DrawTrackerView();
-    tracker_card.End();
   }
+  tracker_card.End();
   
   // Instrument Editor Card
   if (instrument_card.Begin(card_manager.GetVisibilityFlag("music.instrument_editor"))) {
     DrawInstrumentEditor();
-    instrument_card.End();
   }
+  instrument_card.End();
   
   // Assembly View Card
   if (assembly_card.Begin(card_manager.GetVisibilityFlag("music.assembly"))) {
     assembly_editor_.InlineUpdate();
-    assembly_card.End();
   }
+  assembly_card.End();
 
   return absl::OkStatus();
 }

src/app/editor/sprite/sprite_editor.cc

@@ -57,15 +57,16 @@ absl::Status SpriteEditor::Update() {
   custom_card.SetDefaultSize(800, 600);
 
   // Get visibility flags from card manager and pass to Begin()
+  // Always call End() after Begin() - End() handles ImGui state safely
   if (vanilla_card.Begin(card_manager.GetVisibilityFlag("sprite.vanilla_editor"))) {
     DrawVanillaSpriteEditor();
-    vanilla_card.End();
   }
+  vanilla_card.End();
 
   if (custom_card.Begin(card_manager.GetVisibilityFlag("sprite.custom_editor"))) {
     DrawCustomSprites();
-    custom_card.End();
   }
+  custom_card.End();
 
   return status_.ok() ? absl::OkStatus() : status_;
 }

src/app/gui/app/editor_layout.cc

@@ -250,12 +250,14 @@ void EditorCard::SetPosition(Position pos) {
 bool EditorCard::Begin(bool* p_open) {
   // Check visibility flag first - if provided and false, don't show the card
   if (p_open && !*p_open) {
+    imgui_begun_ = false;
     return false;
   }
   
   // Handle icon-collapsed state
   if (icon_collapsible_ && collapsed_to_icon_) {
     DrawFloatingIconButton();
+    imgui_begun_ = false;
     return false;
   }
   
@@ -320,6 +322,9 @@ bool EditorCard::Begin(bool* p_open) {
                              closable_ ? actual_p_open : nullptr, 
                              flags);
   
+  // Mark that ImGui::Begin() was called - End() must always be called now
+  imgui_begun_ = true;
+  
   // Register card window for test automation
   if (ImGui::GetCurrentWindow() && ImGui::GetCurrentWindow()->ID != 0) {
     std::string card_path = absl::StrFormat("EditorCard:%s", title_.c_str());
@@ -332,12 +337,16 @@ bool EditorCard::Begin(bool* p_open) {
 }
 
 void EditorCard::End() {
+  // Only call ImGui::End() and pop styles if ImGui::Begin() was called
+  if (imgui_begun_) {
     // Check if window was focused this frame
     focused_ = ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows);
     
     ImGui::End();
     ImGui::PopStyleColor(2);
     ImGui::PopStyleVar(2);
+    imgui_begun_ = false;
+  }
 }
 
 void EditorCard::Focus() {

src/app/gui/app/editor_layout.h

@@ -98,9 +98,9 @@ class Toolset {
  * tile_card.SetPosition(CardPosition::Right);
  * 
  * if (tile_card.Begin()) {
- *   // Draw tile selector content
- *   tile_card.End();
+ *   // Draw tile selector content when visible
  * }
+ * tile_card.End();  // Always call End() after Begin()
  * ```
  */
 class EditorCard {
@@ -154,6 +154,7 @@ class EditorCard {
   bool first_draw_ = true;
   bool focused_ = false;
   bool* p_open_ = nullptr;
+  bool imgui_begun_ = false;  // Track if ImGui::Begin() was called
   
   // UX enhancements
   bool headless_ = false;  // Minimal chrome, no title bar