OK.
For more cros-version compatibility:
administrator/components/com_vminvoice/views/order/tmpl/default.php
about the line 17
JHTML::_('behavior.mootools');
change to this:
if(JVERSION<3) { JHTML::_('behavior.mootools');
} else { JHtml::_('behavior.framework'); }
Logical condition, checking Joomla version and setting proper mootools injection method.
I made change of the previous verion deleting ',true' from :
JHTML::_('behavior.framework', true);
I think it's no need to load MooTools More libraries, and that 'true' was makeing it (was loading MooTools More libraries). If I'm wrong, just live that 'true' alone.
But that is more for developers information :). Because if someone install it on J3 and VM3 he wouldn't need both methods alternately.
The rest of thing looks fine - have a little problem with deleteing orders from vminvoice but looks to work fine now
don't know why ? :) but works.
THE END.