Flashing page border in DocView

[Guido Van Hoecke]

Just 'discovered' DocView mode to view pdf files :)

One aspect does annoy me though: it shows the page border with a fine line.
No problem with that, but it is flashing every second. That is a definite
no-no!

I failed to detect how I can turn this into a steady line or have it
disappear completely. Either solution is ok for me.

M-x version:
GNU Emacs 24.3.1 (x86_64-apple-darwin, NS apple-appkit-1187.37) of
2013-05-18 on zac.local

TIA for your help.

Guido