Just as an aside, do you plan to integrate the toolbar into the main MJ module? I know you would need to edit the Jenkins job and such, but aside from that? I'm curious How about holding a static list of your buttons, along with some "use" counter? As soon as the use counter is zero, you could set the buttons to visible=false. There is no real need to actually Destroy() them because they are very lightweight. I already do...? https://github.com/blizzy78/ksp_toolbar/commit/9b6f9a8289f3ba477b413e551ea00976d32e2299 (This commit made it into Toolbar 1.1.0)