macosx: fix memleak in position formatter

modules/gui/macosx/misc.m

@@ -796,10 +796,17 @@ void _drawFrameInRect(NSRect frameRect)
     NSMutableCharacterSet *nonNumbers = [[[NSCharacterSet decimalDigitCharacterSet] invertedSet] mutableCopy];
     [nonNumbers removeCharactersInString:@":"];
     o_forbidden_characters = [nonNumbers copy];
+    [nonNumbers release];
 
     return self;
 }
 
+- (void)dealloc
+{
+    [o_forbidden_characters release];
+    [super dealloc];
+}
+
 - (NSString*)stringForObjectValue:(id)obj
 {
     return obj;