gtk:text-visibility (object)

object -- a gtk:text widget
visible -- a boolean whether the text is visible

The accessor for the visibility slot gets or sets whether the text in the text entry is visible. When visibility is set to false, characters are displayed as the invisible char, and will also appear that way when the text in the text entry is copied to the clipboard.

By default, GTK picks the best invisible character available in the current font, but it can be changed with the gtk:text-invisible-char function.

Note that you probably want to set the input-purpose property to the :password or :pin value to inform input methods about the purpose of the text entry, in addition to setting the visibility property to false.