Enable/Disable View menu items according to state

- Disable all Game List/Grid related options while System Display is active.
  Reenable when switching back to List/Grid.
- Disable Game List/Grid exclusive options when switching to the opposite view;
- Disable "Clear List Background" when a background is not set;
- Enable tooltips for menu items;

src/duckstation-qt/mainwindow.cpp

@@ -528,6 +528,26 @@ void MainWindow::updateDisplayRelatedActions(bool has_surface, bool fullscreen)
   m_ui.menuWindowSize->setEnabled(s_system_valid && !s_system_starting && has_surface && !fullscreen);
   m_ui.actionFullscreen->setEnabled(has_surface && !s_system_starting);
   m_ui.actionFullscreen->setChecked(fullscreen);
+
+  updateGameListRelatedActions(has_surface);
+}
+
+void MainWindow::updateGameListRelatedActions(bool running)
+{
+  bool game_grid = m_game_list_widget->isShowingGameGrid();
+  bool game_list = m_game_list_widget->isShowingGameList();
+  bool has_background = Host::GetBaseStringSettingValue("UI", "GameListBackgroundPath") != "";
+  bool starting_or_running = (s_system_starting || running);
+
+  m_ui.actionMergeDiscSets->setDisabled(starting_or_running);
+  m_ui.actionShowLocalizedTitles->setDisabled(starting_or_running);
+  m_ui.actionShowGameIcons->setDisabled(starting_or_running || !game_list);
+  m_ui.actionGridViewShowTitles->setDisabled(starting_or_running || !game_grid);
+  m_ui.actionViewZoomIn->setDisabled(starting_or_running);
+  m_ui.actionViewZoomOut->setDisabled(starting_or_running);
+  m_ui.actionGridViewRefreshCovers->setDisabled(starting_or_running || !game_grid);
+  m_ui.actionChangeGameListBackground->setDisabled(starting_or_running);
+  m_ui.actionClearGameListBackground->setDisabled(starting_or_running || !has_background);
 }
 
 void MainWindow::focusDisplayWidget()
@@ -1441,12 +1461,14 @@ void MainWindow::onViewStatusBarActionToggled(bool checked)
 void MainWindow::onViewGameListActionTriggered()
 {
   m_game_list_widget->showGameList();
+  updateGameListRelatedActions(false);
   switchToGameListView();
 }
 
 void MainWindow::onViewGameGridActionTriggered()
 {
   m_game_list_widget->showGameGrid();
+  updateGameListRelatedActions(false);
   switchToGameListView();
 }
 
@@ -2659,6 +2681,7 @@ void MainWindow::onViewChangeGameListBackgroundTriggered()
   Host::SetBaseStringSettingValue("UI", "GameListBackgroundPath", relative_path.c_str());
   Host::CommitBaseSettingChanges();
   m_game_list_widget->updateBackground(true);
+  m_ui.actionClearGameListBackground->setEnabled(true);
 }
 
 void MainWindow::onViewClearGameListBackgroundTriggered()
@@ -2666,6 +2689,7 @@ void MainWindow::onViewClearGameListBackgroundTriggered()
   Host::DeleteBaseSettingValue("UI", "GameListBackgroundPath");
   Host::CommitBaseSettingChanges();
   m_game_list_widget->updateBackground(true);
+  m_ui.actionClearGameListBackground->setEnabled(false);
 }
 
 void MainWindow::onSettingsTriggeredFromToolbar()

src/duckstation-qt/mainwindow.h

@@ -274,6 +274,7 @@ private:
   void destroyDisplayWidget(bool show_game_list);
   void updateDisplayWidgetCursor();
   void updateDisplayRelatedActions(bool has_surface, bool fullscreen);
+  void updateGameListRelatedActions(bool running);
   void exitFullscreen(bool wait_for_completion);
 
   void doSettings(const char* category = nullptr);

src/duckstation-qt/mainwindow.ui

@@ -37,6 +37,9 @@
     <property name="title">
      <string>&amp;System</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <widget class="QMenu" name="menuChangeDisc">
      <property name="title">
       <string>Change Disc</string>
@@ -93,6 +96,9 @@
     <property name="title">
      <string>S&amp;ettings</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <addaction name="actionViewGameProperties"/>
     <addaction name="separator"/>
     <addaction name="actionInterfaceSettings"/>
@@ -120,6 +126,9 @@
     <property name="title">
      <string>&amp;Help</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <addaction name="actionGitHubRepository"/>
     <addaction name="actionDiscordServer"/>
     <addaction name="separator"/>
@@ -133,6 +142,9 @@
     <property name="title">
      <string>&amp;Debug</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <widget class="QMenu" name="menuRenderer">
      <property name="title">
       <string>Switch GPU Renderer</string>
@@ -192,6 +204,9 @@
     <property name="title">
      <string>&amp;View</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <widget class="QMenu" name="menuWindowSize">
      <property name="title">
       <string>&amp;Window Size</string>
@@ -227,6 +242,9 @@
     <property name="title">
      <string>&amp;Tools</string>
     </property>
+    <property name="toolTipsVisible">
+     <bool>true</bool>
+    </property>
     <addaction name="actionOpenDataDirectory"/>
     <addaction name="separator"/>
     <addaction name="actionMemoryCardEditor"/>