I'd like to see true multi-screen support, i.e.:

* Option to clear all displays during breaks. (default)
* Option to clear only the primary display during breaks.

* Option to configure on which display to show the exercises
  (Somewhat related to https://issues.workrave.org/show_bug.cgi?id=589
   "Make multi-screen behaviour configurable?")

  (Somewhat related to https://issues.workrave.org/show_bug.cgi?id=453
   "No multi-display support")


Rationale:
Currently, secondary displays continue showing 'normal' content during breaks. As a consequence, the user still sees that content and just continues thinking about the work to be done, instead of truly take a break.