Sets the default size of a window.
If the window’s “natural” size (its size request) is larger than the default, the default will be ignored.
Unlike [method@Gtk.Widget.set_size_request], which sets a size request for a widget and thus would keep users from shrinking the window, this function only sets the initial size, just as if the user had resized the window themselves. Users can still shrink the window again as they normally would. Setting a default size of -1 means to use the “natural” default size (the size request of the window).
The default size of a window only affects the first time a window is shown; if a window is hidden and re-shown, it will remember the size it had prior to hiding, rather than using the default size.
Windows can’t actually be 0x0 in size, they must be at least 1x1, but passing 0 for
height is OK,
resulting in a 1x1 default size.
If you use this function to reestablish a previously saved window size, note that the appropriate size to save is the one returned by [ method@Gtk.Window.get_default_size]. Using the window allocation directly will not work in all circumstances and can lead to growing or shrinking windows.
width in pixels, or -1 to unset the default width
height in pixels, or -1 to unset the default height