Hi,
Only a little thing but still irritating nonetheless. Happens in 4.55 Windows x64 but has been a problem for a long time. Not sure which version it started in.
If you add a plugin to a track that takes some time to load (Native Instruments plugins often take a while to load, have also noticed it on Nexus 2), the plugin window briefly says 'Not Responding' and the Pin icon in the top right gets stuck. Even after the window is closed it stays there, stuck on the screen in the middle of nowhere.
See the following licecap....
link
Pin stuck on screen (FIXED)
Threaded Mode