Calling SetNewScreen when not the top screen on the stack only replaces the

top screen.  This allows a screen to push a helper screen, which can then
enter an entirely separate set of helper screens before one pops back.
(For example, a screen could push ScreenServiceOptions to enter the options
menu, which then replaces itself with the various options menus, and finally
pops back to the original screen when the player backs out entirely.)  (Some
support is still missing to allow non-special-case use of this; coming soon ...)

However, in rare cases we want to kill all screens on the stack, regardless
of how many there are (operator menu).  Fix that case.

stepmania/src/ScreenManager.cpp

@@ -280,7 +280,7 @@ static bool g_bIsConcurrentlyLoading = false;
 /* Pop the top screen off the stack, sending SM_LoseFocus messages and
  * returning the message the popped screen wants sent to the new top
  * screen.  Does not send SM_GainFocus. */
-ScreenMessage ScreenManager::PopTopScreenInternal()
+ScreenMessage ScreenManager::PopTopScreenInternal( bool bSendLoseFocus )
 {
 	if( g_ScreenStack.empty() )
 		return SM_None;
@@ -288,7 +288,8 @@ ScreenMessage ScreenManager::PopTopScreenInternal()
 	LoadedScreen ls = g_ScreenStack.back();
 	g_ScreenStack.erase( g_ScreenStack.end()-1, g_ScreenStack.end() );
 
-	ls.m_pScreen->HandleScreenMessage( SM_LoseFocus );
+	if( bSendLoseFocus )
+		ls.m_pScreen->HandleScreenMessage( SM_LoseFocus );
 
 	if( g_setPersistantScreens.find(ls.m_pScreen->GetName()) != g_setPersistantScreens.end() )
 	{
@@ -698,6 +699,23 @@ void ScreenManager::PopTopScreen( ScreenMessage SM )
 	m_PopTopScreen = SM;
 }
 
+/* Clear the screen stack; only used before major, unusual state changes,
+ * such as resetting the game or jumping to the service menu.  Don't call
+ * from inside a screen. */
+void ScreenManager::PopAllScreens()
+{
+	if( g_ScreenStack.empty() )
+		return;
+
+	/* Make sure only the top screen receives LoseFocus. */
+	bool bFirst = true;
+	while( !g_ScreenStack.empty() )
+	{
+		PopTopScreenInternal( bFirst );
+		bFirst = false;
+	}
+}
+
 void ScreenManager::PostMessageToTopScreen( ScreenMessage SM, float fDelay )
 {
 	Screen* pTopScreen = GetTopScreen();