[Screen] add HandleBackButton (for people who know what they're doing ;) [people making multi-state menus using the MK2ULTRA method])

Docs/Changelog_sm-ssc.txt

@@ -10,12 +10,13 @@ supported but exist anyways.)
 _____________________________________________________________________________
 
 ================================================================================
-sm-ssc v1.2 | 201012xx
+sm-ssc v1.2 | 201101xx
 --------------------------------------------------------------------------------
 
-20101231
+20110101
 --------
-* [ScreenGameplay] Fixed "Gameplay ### combo" announcer messages. [neothe0ne]
+* [Screen] Added HandleBackButton metric; useful for custom menus that need to
+  use the Back button for more user-friendly canceling. [freem]
 
 20101230
 --------

Themes/_fallback/metrics.ini

@@ -1198,6 +1198,7 @@ BlinkPlayersBest=true
 ScreenInitCommand=
 ScreenOnCommand=
 AllowOperatorMenuButton=true
+HandleBackButton=true
 RepeatRate=-1
 RepeatDelay=-1
 PrepareScreens=

src/Screen.cpp

@@ -42,6 +42,7 @@ bool Screen::SortMessagesByDelayRemaining( const Screen::QueuedScreenMessage &m1
 void Screen::Init()
 {
 	ALLOW_OPERATOR_MENU_BUTTON.Load( m_sName, "AllowOperatorMenuButton" );
+	HANDLE_BACK_BUTTON.Load( m_sName, "HandleBackButton" );
 	REPEAT_RATE.Load( m_sName, "RepeatRate" );
 	REPEAT_DELAY.Load( m_sName, "RepeatDelay" );
 	LIGHTS_MODE.Load( m_sName, "LightsMode" );
@@ -204,7 +205,10 @@ void Screen::Input( const InputEventPlus &input )
 	case GAME_BUTTON_BACK:
 		// Don't make the user hold the back button if they're pressing escape and escape is the back button.
 		if( !PREFSMAN->m_bDelayedBack || input.type==IET_REPEAT || (input.DeviceI.device == DEVICE_KEYBOARD && input.DeviceI.button == KEY_ESC) )
-			this->MenuBack( input );
+		{
+			if( HANDLE_BACK_BUTTON )
+				this->MenuBack( input );
+		}
 		return;
 	case GAME_BUTTON_START:	this->MenuStart	( input );	return;
 	case GAME_BUTTON_SELECT:this->MenuSelect( input );	return;

src/Screen.h

@@ -80,6 +80,7 @@ protected:
 	InputQueueCodeSet	m_Codes;
 
 	ThemeMetric<bool>	ALLOW_OPERATOR_MENU_BUTTON;
+	ThemeMetric<bool>	HANDLE_BACK_BUTTON;
 	ThemeMetric<float>	REPEAT_RATE;
 	ThemeMetric<float>	REPEAT_DELAY;
 	ThemeMetric<LightsMode> LIGHTS_MODE;