Yes, there is the problem with Trimmer Plugin.
It's displayed is in settings area of the WMP, so if you open another tool e.g. "play speed settings" it will close the plugin's window and you should open plugin again.
We will try to make Option to display plugin in a separate window in future updates.
But for now you can do it manually by downloading sepW.zip
1. Close WMP if it was opened.
2. Extract an archive and open Enable_SepW.reg to add entry to registry for displaying plugin in separate window.
If you would like to turn of this just reinstall the plugin.