Resolve issue 76: add a new metric.

One can now define whether Ctrl+Up expands the selection
or shrinks it, and vice~versa with Ctrl+Down.

Docs/Changelog_sm-ssc.txt

@@ -19,6 +19,9 @@ sm-ssc v1.2.4 | 20110???
   saved. [AJ, Wolfman2000]
 * [ScreenOptionsEdit] Fix bug number 186, where people could try to edit or
   share songs when they didn't have any. [Wolfman2000]
+* [ScreenEdit] Add a metric to switch Ctrl+Up and Ctrl+Down. This is for
+  easier compatibility with prior versions of SM. It defaults to false.
+  [Wolfman2000]
 
 20110316
 --------

Themes/_fallback/metrics.ini

@@ -3628,6 +3628,7 @@ ShowHelp=false
 AllowOperatorMenuButton=false
 ShowCreditDisplay=false
 ShowStyleIcon=false
+InvertScrollSpeedButtons=false
 TimerSeconds=-1
 EditModifiers="no reverse"
 EditHelpX=SCREEN_LEFT+4

src/ScreenEdit.cpp

@@ -1243,6 +1243,8 @@ static int FindAttackAtTime( const AttackArray& attacks, float fStartTime )
 
 static LocalizedString SWITCHED_TO		( "ScreenEdit", "Switched to" );
 static LocalizedString NO_BACKGROUNDS_AVAILABLE	( "ScreenEdit", "No backgrounds available" );
+static ThemeMetric<bool> INVERT_SCROLL_BUTTONS ( "ScreenEdit", "InvertScrollSpeedButtons" );
+
 void ScreenEdit::InputEdit( const InputEventPlus &input, EditButton EditB )
 {
 	if( input.type == IET_RELEASE )
@@ -1364,10 +1366,10 @@ void ScreenEdit::InputEdit( const InputEventPlus &input, EditButton EditB )
 			{
 			DEFAULT_FAIL(EditB);
 			case EDIT_BUTTON_SCROLL_SPEED_DOWN:
-				--iSpeed;
+				INVERT_SCROLL_BUTTONS ? ++iSpeed : --iSpeed;
 				break;
 			case EDIT_BUTTON_SCROLL_SPEED_UP:
-				++iSpeed;
+				INVERT_SCROLL_BUTTONS ? --iSpeed : ++iSpeed;
 				break;
 			}
 			iSpeed = clamp( iSpeed, 0, (int) ARRAYLEN(fSpeeds)-1 );