ScreenType is being overloaded in incompatible ways:

- the editor sets "system_menu" to trick StepMania.cpp into not
   allowing the operator menu button, to prevent losing data;
 - the editor also sets "gameplay" in "playback" mode to influence
   ScreenSyncOverlay and ScreenDebugOverlay; this breaks the above,
   allowing scroll lock in play mode.

A similar problem happens when we push screens: scroll lock works
in the MiniMenus in the editor.

It's semantically unintuitive to call the editor a "system_menu", anyway.

Split out AllowOperatorMenuButton, and use it directly.  Check all
screens, and don't allow it if any screen on the stack disallows it.

stepmania/src/Screen.h

@@ -56,6 +56,7 @@ public:
 
 	virtual bool UsesBackground() const { return true; }	// override and set false if this screen shouldn't load a background
 	virtual ScreenType GetScreenType() const { return ALLOW_OPERATOR_MENU_BUTTON ? game_menu : system_menu; }
+	bool AllowOperatorMenuButton() const { return ALLOW_OPERATOR_MENU_BUTTON; }
 
 	static bool JoinInput( const MenuInput &MenuI );	// return true if a player joined
 

stepmania/src/ScreenEdit.h

@@ -160,7 +160,7 @@ public:
 	virtual void HandleScreenMessage( const ScreenMessage SM );
 
 protected:
-	virtual ScreenType GetScreenType() const { return m_EditState==STATE_PLAYING ? gameplay : system_menu; }
+	virtual ScreenType GetScreenType() const { return m_EditState==STATE_PLAYING ? gameplay : ScreenWithMenuElements::GetScreenType(); }
 
 	void TransitionEditState( EditState em );
 	void ScrollTo( float fDestinationBeat );

stepmania/src/ScreenManager.cpp

@@ -283,6 +283,17 @@ Screen *ScreenManager::GetTopScreen()
 	return g_ScreenStack[g_ScreenStack.size()-1].m_pScreen;
 }
 
+bool ScreenManager::AllowOperatorMenuButton() const
+{
+	FOREACH( LoadedScreen, g_ScreenStack, s )
+	{
+		if( !s->m_pScreen->AllowOperatorMenuButton() )
+			return false;
+	}
+
+	return true;
+}
+
 bool ScreenManager::IsStackedScreen( const Screen *pScreen ) const
 {
 	/* True if the screen is in the screen stack, but not the first. */

stepmania/src/ScreenManager.h

@@ -40,6 +40,7 @@ public:
 	void PopTopScreen( ScreenMessage SM );
 	void PopAllScreens();
 	Screen *GetTopScreen();
+	bool AllowOperatorMenuButton() const;
 
 	// System messages
 	void SystemMessage( const RString &sMessage );

stepmania/src/StepMania.cpp

@@ -1223,7 +1223,7 @@ bool HandleGlobalInputs( const InputEventPlus &input )
 		/* Global operator key, to get quick access to the options menu. Don't
 		 * do this if we're on a "system menu", which includes the editor
 		 * (to prevent quitting without storing changes). */
-		if( SCREENMAN->GetTopScreen()->GetScreenType() != system_menu )
+		if( SCREENMAN->AllowOperatorMenuButton() )
 		{
 			SCREENMAN->SystemMessage( SERVICE_SWITCH_PRESSED );
 			GAMESTATE->Reset();