Clicking the sheep currently results in showing/hiding the counters. What about make the single-click action configurable? Or even add a configurable double-click action? Potential actions:

* Show/hide the counters
* Suspend/resume the counters
* Reset the counters
* Take a break
* Add some minutes

The configured action should also be executable using a global key shortcut.

Rationale:
A person gets at my desk and asks something. While talking, the screen suddenly turns grey, upps... With such global key shortcut, I could very easily suspend any Workrave activity, and resume once the person has left my desk.