After I installed Good ol Sidebar 1.0.6, entering a term in the 'Search' portion of 2 Pane Bookmarks would do nothing. No search would be made. Reverting back to Good ol Sidebar 1.0.5 solved the problem, and the Search function worked as it should.
This will be fixed in the next release. In v1.0.6, I've added the 2-pane feature for both History and Bookmarks into TGS itself and wasn't able to add a check for 2 Pane Bookmarks if it is installed because it will conflict with the feature. For more information about this, see this post
Let us know when the new version is available.
I had not caught your 1.0.6 statement that you had added the two pane feature. So I opened a portable version of PM 27.9.2, which has the identical addons and themes of my desktop version. On the portable, I disabled 2 Pane Bookmarks, removed Good ol Sidebar 1.5, and installed Good ol Sidebar 1.0.6.
I was able to get the 2-pane feature, but I ran into a couple of problems.
1. Right clicking on an entry in the top pane would not display the dropdown menu. What I got was a very small pane with an up arrow and a down arrow. That was all.
2. When I tried to do a search, BOTH panes showed the search results, rather than just the bottom pane. I thought I saw somewhere in your FAQ or instructions that adding a P2 preceding the search word would search just the bottom pane, but that did not work, and I could never get back to wherever I saw that note about how to conduct the search on just one pane.
So I reverted my portable version back to Good ol Sidebar 1.5 and enabled 2 Pane Bookmarks.