Displaying Active Work Coordinate System

I'm trying to modify a GladeVCP to have a label that displays the current active work coordinate system.  And to put it bluntly Python is kicking my butt.  So how exactly would one set up the python handler file to read the linuxcnc stat.g5x_index then use that to change the string that is displayed in the gtk label? 
In my  GladeVCP the label I want to use is named "work_coord_label" and I would like the label to read "G54(front)" when the G54 coordinate system is active, and "G55(Rear)" when G55 is active.  (The other coordinate systems can meerly read G56,G57... as there is no plan to use them at this point.)

PS.  This is on a machine running Linuxcnc ver 2.7.25 (And I don't think I can ugrade because this system requires a very low latency RTAI config that I don't think I can easily replicate with newer versions.)