Make it possible to have implementations in different toolkits.

Also, make it possible to share the headers.

OGWindow.m

@@ -1,92 +0,0 @@
-#import "OGWindow.h"
-
-@interface OGWindow ()
-- (BOOL)OG_willClose;
-@end
-
-static gboolean
-willClose(GtkWidget *widget, GdkEvent *event, gpointer data)
-{
-	return ([(OGWindow*)data OG_willClose] ? FALSE : TRUE);
-}
-
-@implementation OGWindow
-@synthesize delegate;
-
-+ window
-{
-	return [[[self alloc] init] autorelease];
-}
-
-- init
-{
-	self = [super init];
-
-	widget = gtk_window_new(GTK_WINDOW_TOPLEVEL);
-	g_signal_connect(G_OBJECT(widget), "delete-event",
-	    G_CALLBACK(willClose), self);
-
-	g_signal_connect(G_OBJECT(widget), "destroy", G_CALLBACK(og_destroy),
-	    self);
-	[self retain];
-
-	return self;
-}
-
-- (OFString*)title
-{
-	return [OFString stringWithUTF8String:
-	    gtk_window_get_title(GTK_WINDOW(widget))];
-}
-
-- (void)setTitle: (OFString*)title
-{
-	gtk_window_set_title(GTK_WINDOW(widget), [title UTF8String]);
-}
-
-- (of_point_t)position
-{
-	gint x, y;
-
-	gtk_window_get_position(GTK_WINDOW(widget), &x, &y);
-
-	return of_point(x, y);
-}
-
-- (void)setPosition: (of_point_t)position
-{
-	gtk_window_move(GTK_WINDOW(widget), position.x, position.y);
-}
-
-- (of_dimension_t)dimension
-{
-	gint width, height;
-
-	gtk_window_get_size(GTK_WINDOW(widget), &width, &height);
-
-	return of_dimension(width, height);
-}
-
-- (void)setDimension: (of_dimension_t)dimension
-{
-	gtk_window_resize(GTK_WINDOW(widget),
-	    dimension.width, dimension.height);
-}
-
-- (void)addChild: (OGWidget*)child
-{
-	gtk_container_add(GTK_CONTAINER(widget), child->widget);
-}
-
-- (BOOL)OG_willClose
-{
-	OFAutoreleasePool *pool = [OFAutoreleasePool new];
-
-	if ([delegate respondsToSelector: @selector(windowWillClose:)])
-		return [delegate windowWillClose: self];
-
-	[pool release];
-
-	return YES;
-}
-@end