Added auto-size support during dw_window_set_pos() on OS/2, Mac and Windows. Since dw_window_set_pos() can have unexpected results on unsized windows... if a window is unsized attempt to auto-size at that point. Auto-sizing during dw_window_set_pos() will cause auto-sizing not to happen during dw_window_show() so make sure it is completely packed before setting the position.