I've seen that others have reported bug of Toggle Sidebar in the front end.

I have problems with the Toggle in back end. It doesn't toggle at all and nothing happens when I click on it. Any suggestions?

The problem seem to that SIG is the problem. In Items with galleries there is no problem to use the Toggle Sidebar, only on items with galleries. When I disable the SIG the problem dissappear.

Could someone try to fix this soon?

Also found this thread, but no bug report: community.getk2.org/forum/topics/toggle-sidebar-problem