Okay.
Screendumps from the debug menu might not be fixed anytime soon (then again, maybe, who knows?). Read linuxstb's comment on the tracker for the Why.
Nopo, if your WPS is based on pure, current svn then you may use the simulator provided in the extra section of the rockbox downloads :
http://www.rockbox.org/twiki/bin/vie.../RockboxExtras (link at bottom of screen) to test and make the screenshots.
note : screendumps in simulator : F5 or numpad 0 ...
see
http://www.rockbox.org/twiki/bin/view/Main/UiSimulator for all commands.