By default, windows have a close button in the window frame.
Some window managers allow GTK to disable this button. If you
set the deletable property to %FALSE using this function, GTK
will do its best to convince the window manager not to show a
close button. Depending on the system, this function may not
have any effect when called on a window that is already visible,
so you should call it before calling [method@Gtk.Widget.show].
On Windows, this function always works, since there’s no window
manager policy involved.
Sets whether the window should be deletable.
By default, windows have a close button in the window frame. Some window managers allow GTK to disable this button. If you set the deletable property to %FALSE using this function, GTK will do its best to convince the window manager not to show a close button. Depending on the system, this function may not have any effect when called on a window that is already visible, so you should call it before calling [method@Gtk.Widget.show].
On Windows, this function always works, since there’s no window manager policy involved.