Adapt Lrcshow-X with Gmusicbrowser is really easy. Only need to add Gmusicbrowser in the supportedPlayers list of the file players/__init__.py and to do a sed in a term:

sed 's/songbird/gmusicbrowser/g' <players/songbird.py >players/gmusicbrowser.py

Now you can launch lrcshow-X (after activating mpris1/2 plugins un Gmusicbrowser prefs.

Et voilà !!