Following myself up here... the behaviour I am seeing appears to be related to a known problem as reported on the ptk mailing list here and acknowledged here by Nick Ing-Simmons.

I will submit a further bug report and update this node when I have more information

Update: I have a patchset to test- http://www.cpan.org/modules/by-authors/id/L/LU/LUSOL/Tk804.024.patches-0.1.tar.gz gratefull thanks to Slaven Rezic, will further update when I have had a chance to test the patchset.

Update: Applied the patchset all is now working as expected. Thanks again to Slaven and also to Steve Lidie and any-one else who put work into the patchset.

--
Do not seek to follow in the footsteps of the wise. Seek what they sought. -Basho