gtk: draw the progress only on the text area
gtk: draw the progress only on the text area

so it doesn't extend under GtkSpinButton's buttons.

Distrotech/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Unity-Technologies/gtk,Distrotech/gtk,Distrotech/gtk,Unity-Technologies/gtk,Distrotech/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2