Causes the given text to appear superimposed on the progress bar.
If text is NULL and "show-text" is TRUE, the current
value of "fraction" will be displayed as a percentage.
If text is non-NULL and "show-text" is TRUE, the text will
be displayed. In this case, it will not display the progress percentage.
If text is the empty string, the progress bar will still be styled and sized
suitably for containing text, as long as "show-text" is TRUE.
Causes the given text to appear superimposed on the progress bar. If text is NULL and "show-text" is TRUE, the current value of "fraction" will be displayed as a percentage. If text is non-NULL and "show-text" is TRUE, the text will be displayed. In this case, it will not display the progress percentage. If text is the empty string, the progress bar will still be styled and sized suitably for containing text, as long as "show-text" is TRUE.