Linux requires a `gtk_menu_bar` for a gtk_window to display a menu. For the `systray` a `gtk_menu` is needed instead. This change creates the correct type of `impl` for the `Menu` depending on how it is being used.
This reverts commit b317efaf2c, reversing changes made to 29b9c5200f.
b317efaf2c
29b9c5200f