Sets whether the progress bar will show a text in addition to the bar itself. The shown text is either the value of the #GtkProgressBar:text property or, if that is null, the #GtkProgressBar:fraction value, as a percentage.
To make a progress bar that is styled and sized suitably for showing text (even if the actual text is blank), set #GtkProgressBar:show-text to true and #GtkProgressBar:text to the empty string (not null).
Builder instance for fluent chaining
Set showText property.