Entry.setVisibility

Sets whether the contents of the entry are visible or not. When visibility is set to false, characters are displayed as the invisible char, and will also appear that way when the text in the entry widget is copied elsewhere.

By default, GTK+ picks the best invisible character available in the current font, but it can be changed with [gtk.entry.Entry.setInvisibleChar].

Note that you probably want to set #GtkEntry:input-purpose to [gtk.types.InputPurpose.Password] or [gtk.types.InputPurpose.Pin] to inform input methods about the purpose of this entry, in addition to setting visibility to false.