Do use disabled control text color for wxStaticText in OS X.

Contrary to an old comment, using it seems to work, while using
secondarySelectedControlColor results in incorrect appearance, different from
the other disabled controls and, worse, makes the labels unreadable as their
colour is too close to that of the background inside nested panels.

See #10524.

src/osx/cocoa/stattext.mm

@@ -60,10 +60,8 @@
 
     [super setEnabled: flag]; 
     
-    if (![self drawsBackground]) { 
-        // Static text is drawn incorrectly when disabled. 
-        // For an explanation, see 
-        // http://www.cocoabuilder.com/archive/message/cocoa/2006/7/21/168028 
+    if (![self drawsBackground])
+    { 
         if (flag)
         { 
             if (m_textColor)
@@ -76,7 +74,7 @@
                 [m_textColor release];
                 m_textColor = [[self textColor] retain];
             }
-            [self setTextColor: [NSColor secondarySelectedControlColor]]; 
+            [self setTextColor: [NSColor disabledControlTextColor]]; 
         } 
     } 
 }