Juan Carlos Pérez
Would it be possible for you to release a new version that supports the new versions of GTK being shipped with pidgin.
The latest version of the plugin doesn't play nicely with the latest(s) GTK and the hide taskbar entry doesn't work anymore.
This bug with the hide taskbar entry is a GTK bug and not a Extended Prefs bug.
If you look at the bug that was filed a few months ago regarding this (https://sourceforge.net/tracker/?func=detail&aid=1905379&group_id=107659&atid=648308) there is a work around. Basically downgrade your GTK version to the one listed in the bug and it should work for you.
If there are other problems with Extended Prefs and GTK, you can file a bug and I can have a look at it.