how can i detect if i am in full screen of some program?

Hello.
i worte some good script with amazing idea for myself and all of it do the job Perfectly.

but it is is required that this specific job will not execute whan i for example playing movie or listen to music.
so i have to do a condition that checks if i am not do such things.

i know that i can program that it will look in to ini file ot txt file which contains a list of programs that when they runing so the job will not execute but i wondering if there is a better way that the script will know alone when to do the job and when not.

thanks for the helpers!