A fixed container is a container that keeps it's children at fixed locations and give them fixed sizes, both given in pixels.
Example: GTK.Fixed()->put(GTK.Label("100,100"), 100, 100)->put(GTK.Label("0,0"), 0, 0)->set_usize(150,115)
GTK.Fixed()->put(GTK.Label("100,100"), 100, 100)->put(GTK.Label("0,0"), 0, 0)->set_usize(150,115)
GTK.FileSelection()->show_fileop_buttons()
