Make it possible to have implementations in different toolkits.

Also, make it possible to share the headers.

OGHBox.m

@@ -1,16 +0,0 @@
-#import "OGHBox.h"
-
-@implementation OGHBox
-- init
-{
-	self = [super init];
-
-	widget = gtk_hbox_new(FALSE, 0);
-
-	g_signal_connect(G_OBJECT(widget), "destroy", G_CALLBACK(og_destroy),
-	    self);
-	[self retain];
-
-	return self;
-}
-@end