From http://www.openvpms.org/forum/it-possible-change-help-url:

Clicking help on the top menu line (or keying Alt-H) brings up a window which only allows you to go the the OPV site.

Is it possible to tailor a) the pop-up window that currently contains the version number or and the one "Help Topics" link; b) the URL that "Help Topics" invokes?

Ahah - after a quick search through the source: b) the URL is set in the messages file as the message helpdialog.topics.link; a) the popup window is hard coded but it would be relatively easy to provide for extra buttons (say helpdialog.topic1.link thru helpdialog.topic9.link) with the code generating the buttons only if the message is present in the message file.

The code is something like the following replacement for lines 81-91 of HelpDialog.java: [warning my java is 10 years rusty]

The above also requires renaming the current help.topics and help.topics.link messages to help.topic0 and help.topic0.link