add alphaValue property... although we don't use it anyway it helps to compile stuff

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/gui/trunk@38840 72102866-910b-0410-8b05-ffd578937521

Source/NSView.m

@@ -630,6 +630,8 @@ GSSetDragTypes(NSView* obj, NSArray *types)
   //_nextKeyView = 0;
   //_previousKeyView = 0;
 
+  _alphaValue = 1.0;
+  
   return self;
 }
 
@@ -1639,6 +1641,18 @@ static NSSize _computeScale(NSSize fs, NSSize bs)
     }
 }
 
+
+- (CGFloat) alphaValue
+{
+  return _alphaValue;
+}
+
+- (void)setAlphaValue: (CGFloat)alpha
+{
+  _alphaValue = alpha;
+}
+
+
 - (NSRect) centerScanRect: (NSRect)aRect
 {
   NSAffineTransform	*matrix;