add ScreenSelectMaster:GetSelectionIndex() Lua binding.

Example usage:
LoadFont("Common normal")..{
	InitCommand=cmd(xy,SCREEN_RIGHT-32,SCREEN_BOTTOM-32;shadowlength,0;horizalign,right);
	OnCommand=cmd(playcommand,"Set");
	SetCommand=function(self)
		local selIdx = SCREENMAN:GetTopScreen():GetSelectionIndex(GAMESTATE:GetMasterPlayerNumber());
		self:settext(selIdx);
	end;
	MenuSelectionChangedMessageCommand=cmd(playcommand,"Set");
};

src/ScreenSelectMaster.cpp

@@ -814,7 +814,7 @@ bool ScreenSelectMaster::ChangeSelection( PlayerNumber pn, MenuDir dir, int iNew
 
 		if( SHOW_ICON )
 		{
-			/* XXX: If !SharedPreviewAndCursor, this is incorrect.  (Nothing uses
+			/* XXX: If !SharedPreviewAndCursor, this is incorrect. (Nothing uses
 			 * both icon focus and !SharedPreviewAndCursor right now.)
 			 * What is SharedPreviewAndCursor? -- Steve */
 			bool bOldStillHasFocus = false;
@@ -1119,15 +1119,15 @@ void ScreenSelectMaster::MenuStart( const InputEventPlus &input )
 		this->PostScreenMessage( SM_BeginFadingOut, fSecs );// tell our owner it's time to move on
 }
 
-/* We want all items to always run OnCommand and either GainFocus or LoseFocus on
- * tween-in.  If we only run OnCommand, then it has to contain a copy of either
- * GainFocus or LoseFocus, which implies that the default setting is hard-coded
- * in the theme.  Always run both.
- * However, the actual tween-in is OnCommand; we don't always want to actually run
- * through the Gain/LoseFocus tweens during initial tween-in.  So, we run the focus
- * command first, do a FinishTweening to pop it in place, and then run OnCommand.
- * This means that the focus command should be position neutral; eg. only use "addx",
- * not "x". */
+/* We want all items to always run OnCommand and either GainFocus or LoseFocus
+ * on tween-in. If we only run OnCommand, then it has to contain a copy of
+ * either GainFocus or LoseFocus, which implies that the default setting is
+ * hard-coded in the theme. Always run both.
+ * However, the actual tween-in is OnCommand; we don't always want to actually
+ * run through the Gain/LoseFocus tweens during initial tween-in. So, we run
+ * the focus command first, do a FinishTweening to pop it in place, and then
+ * run OnCommand. This means that the focus command should be position neutral;
+ * eg. only use "addx", not "x". */
 void ScreenSelectMaster::TweenOnScreen()
 {
 	vector<PlayerNumber> vpns;
@@ -1273,6 +1273,27 @@ float ScreenSelectMaster::GetCursorY( PlayerNumber pn )
 	return spr->GetDestY() + CURSOR_OFFSET_Y_FROM_ICON.GetValue(pn);
 }
 
+// lua start
+#include "LuaBinding.h"
+
+class LunaScreenSelectMaster: public Luna<ScreenSelectMaster>
+{
+public:
+	static int GetSelectionIndex( T* p, lua_State *L ) { lua_pushnumber( L, p->GetSelectionIndexOfPlayer(Enum::Check<PlayerNumber>(L, 1)) ); return 1; }
+	// should I even bother adding this? -aj
+	// would have to make a public function to get this in ssmaster.h:
+	// m_aGameCommands[i].m_sName
+	// static int SelectionIndexToChoiceName( T* p, lua_State *L ){  return 1; }
+
+	LunaScreenSelectMaster()
+	{
+  		ADD_METHOD( GetSelectionIndex );
+	}
+};
+
+LUA_REGISTER_DERIVED_CLASS( ScreenSelectMaster, ScreenWithMenuElements )
+// lua end
+
 /*
  * (c) 2003-2004 Chris Danford
  * All rights reserved.

src/ScreenSelectMaster.h

@@ -39,6 +39,12 @@ public:
 	virtual void HandleScreenMessage( const ScreenMessage SM );
 	virtual bool AllowLateJoin() const { return true; }
 
+	// sm-ssc additions:
+	int GetSelectionIndexOfPlayer(PlayerNumber pn){ return GetSelectionIndex(pn); }
+
+	// Lua
+	virtual void PushSelf( lua_State *L );
+
 protected:
 	enum Page { PAGE_1, PAGE_2, NUM_Page };	// on PAGE_2, cursors are locked together
 	static PlayerNumber GetSharedPlayer();
@@ -75,7 +81,6 @@ protected:
 	map<int,int> m_mapCurrentChoiceToNextChoice[NUM_MenuDir];
 	map<int,int> m_mapCurrentChoiceToNextChoiceB[NUM_MenuDir]; // if using two lists
 
-
 	virtual int GetSelectionIndex( PlayerNumber pn );
 	virtual void UpdateSelectableChoices();
 	bool AnyOptionsArePlayable() const;
@@ -93,16 +98,14 @@ protected:
 	AutoActor	m_sprMore[NUM_Page];
 	// icon is the shared, per-choice piece
 	vector<AutoActor> m_vsprIcon;
-	vector<AutoActor> m_vsprIconB; // used if the user wants two lists
+	vector<AutoActor> m_vsprIconB; // used if a themer wants two lists
 
 	// preview is per-player, per-choice piece
 	vector<AutoActor> m_vsprScroll[NUM_PLAYERS];
-	vector<AutoActor> m_vsprScrollB[NUM_PLAYERS]; // used if the user wants two lists
-
+	vector<AutoActor> m_vsprScrollB[NUM_PLAYERS]; // used if a themer wants two lists
 
 	ActorScroller	m_Scroller[NUM_PLAYERS];
-	ActorScroller	m_ScrollerB[NUM_PLAYERS]; // used if the user wants two lists
-
+	ActorScroller	m_ScrollerB[NUM_PLAYERS]; // used if a themer wants two lists
 
 	// cursor is the per-player, shared by all choices
 	AutoActor	m_sprCursor[NUM_PLAYERS];