That's already possible by using advanced options.
Open the Advanced Options Editor (more details), and add the following value to Mouse Button Control:
Name: taskbaritem|lclick
Value: 1

See the help file for more details.

I couldn't reproduce it. Did you try disabling all options and checking whether the issue still occurs? Then you could re-enable them one by one and find out which option causes the issue.

hmmm would having "launch folder windows in a separate process" account for this?

That shouldn't affect the behavior of the tweaker.

That doesn't look like it. It should be similar to the report on the linked screenshot.
Faulting application name should be explorer.exe.

P.S. did you experience a crash? In general, an error like this (Could not load library (2xx)) is usually followed by a crash of explorer, but not always.

Sorry, I should have mentioned it.
You can find the crash report in the Event Viewer. Look here for instructions:
How do I find event logs when a program crashes?
Thanks.

Please provide a crash report.

Closing as a duplicate of:
http://tweaker.userecho.com/topic/142187-it-would-be-really-great-to-have-the-possibility-to-always-expand-groups-with-more-than-1-item-and/

Thank you for the positive feedback and for the donation!