gtk:text-invisible-char (object)

object -- a gtk:text widget
char -- an unsigned integer for an Unicode character

The accessor for the invisible-char slot of the gtk:text class gets or sets the character to use when masking the content of the text entry in "password mode". Note that GTK does not compute this value unless it needs it, so the value returned by this function is not very useful unless it has been explicitly set. The (setf gtk:text-invisible-char) function sets the character.

By default, GTK picks the best invisible char available in the current font. If you set the invisible char to 0, then the user will get no feedback at all. There will be no text on the screen as they type.