window: Dont take width and height in window constructor

Always set this by scheduling an initial resize.
diff --git a/clients/dnd.c b/clients/dnd.c
index 632e3b9..b4a9c10 100644
--- a/clients/dnd.c
+++ b/clients/dnd.c
@@ -506,7 +506,7 @@
 		return dnd;
 	memset(dnd, 0, sizeof *dnd);
 
-	dnd->window = window_create(display, 400, 400);
+	dnd->window = window_create(display);
 	dnd->widget = frame_create(dnd->window, dnd);
 	window_set_title(dnd->window, "Wayland Drag and Drop Demo");