Gets the icon theme object associated with @display.
If this function has not previously been called for the given
display, a new icon theme object will be created and associated
with the display. Icon theme objects are fairly expensive to create,
so using this function is usually a better choice than calling
[ctor@Gtk.IconTheme.new] and setting the display yourself; by using
this function a single icon theme object will be shared between users.
A unique GtkIconTheme associated with
the given display. This icon theme is associated with the display
and can be used as long as the display is open. Do not ref or unref it.
Gets the icon theme object associated with @display.
If this function has not previously been called for the given display, a new icon theme object will be created and associated with the display. Icon theme objects are fairly expensive to create, so using this function is usually a better choice than calling [ctor@Gtk.IconTheme.new] and setting the display yourself; by using this function a single icon theme object will be shared between users.