CircPerc    A small widget, subclassed from Core, that can be used to indicate
	    the progress that is made by an application, for example in a
	    lengthy computation. This is done by displaying a circle, in which
	    a colored pie-slice indicates the amount of work already done, and
	    in which the remainder of the circle, filled in with another
	    color, indicates the amount of work yet to be done. The percentage
	    done can be indicated with a two decimal accuracy.
