GTimeUtils: a stopwatch and a timer, bundled together as time utilities

GTimeUtils is a collection of simple and small time utilities, namely a stopwatch and a (countdown) timer.

From version 2.0 onwards, both the timer and the stopwatch are of from GNOME Clocks' respective stack pages. Prior to version 2.0, both utilities served more as a practice than anything else. Since I like the modern look of GNOME Clocks, but dislike the fact that all its functionality is combined into one application, I have re-purposed GNOME Clocks' ui files into standalone utilities.