The preferred place to ellipsize the string.
The text will be ellipsized if the progress bar does not have enough room to display the entire string, specified as a pango.types.EllipsizeMode.
Note that setting this property to a value other than pango.types.EllipsizeMode.None has the side-effect that the progress bar requests only enough space to display the ellipsis ("..."). Another means to set a progress bar's width is gtk.widget.Widget.setSizeRequest.
Set ellipsize property.