func (p *progressbar) SetPercent(percent int) {
if percent < 0 || percent > 100 {
panic(fmt.Errorf("given ProgressBar percentage %d out of range", percent))
}
C.gtk_progress_bar_set_fraction(p.pbar, C.gdouble(percent)/100)
}
func gtk_progress_bar_set_fraction(w *C.GtkWidget, percent int) {
p := C.gdouble(percent) / 100
C.gtk_progress_bar_set_fraction(togtkprogressbar(w), p)
}