Index: editor/_source/internals/fck.js
===================================================================
--- editor/_source/internals/fck.js	(revision 1450)
+++ editor/_source/internals/fck.js	(working copy)
@@ -1010,6 +1010,11 @@
 	// The return value indicates if the default behavior of the keystroke must
 	// be cancelled. Let's do that only if the Execute() call explicitly returns "false".
 	var oCommand = FCK.Commands.GetCommand( keystrokeValue ) ;
+
+	// If the command is disabled then ignore the keystroke
+	if ( oCommand.GetState() == FCK_TRISTATE_DISABLED )
+		return false ;
+
 	return ( oCommand.Execute.apply( oCommand, FCKTools.ArgumentsToArray( arguments, 2 ) ) !== false ) ;
 }