Make it possible to have implementations in different toolkits.

Also, make it possible to share the headers.

OGWidget.m

@@ -1,35 +0,0 @@
-#include "OGWidget.h"
-
-void og_destroy(GtkWidget *widget, OGWidget *object)
-{
-	[object release];
-}
-
-@implementation OGWidget
-- init
-{
-	self = [super init];
-
-	@try {
-		if (isa == [OGWidget class])
-			@throw [OFNotImplementedException
-			    exceptionWithClass: isa
-				      selector: @selector(init)];
-	} @catch (id e) {
-		[self release];
-		@throw e;
-	}
-
-	return self;
-}
-
-- (void)show
-{
-	gtk_widget_show_all(widget);
-}
-
-- (void)hide
-{
-	gtk_widget_hide(widget);
-}
-@end