how to print source pid of process triggering windowshade on

I’m facing one strange problem in my application which runs on linux. I’ve few questions related to fvwm:

1> while running automation in my integrated software after few hours one of the window suddenly starts showing as horizontal line, when i checked in fvwm logs, log entry comes as below:
[fvwm.0][LOG]: -: Windowshade on

I’m wondering who is triggering this ‘windowshade on’ command. I have checked in entire code base but didn’t find any call to fvwm

2>Can we enhance fvwm logs to a level where I can find the source pid of the process which is sending this ‘windowshade on’ event?

Please help me here.