I forgot to answer, sorry.
For selected track, monitor "Current" Strip parameter. It's value will be 127 in case this strip is in focus.
"Rude solo" and "Rude mute" are other strip parameters you can monitor, for them which track you specify does not matter, but it should exist (so, just use Track 1).
All 2 parameters was introduced specially for the purpose you want. Note, that all 3 are Read Only. You can not select/unmute/unsolo by attempt to modify them, use special Functions for that ("Select strip", "All" "Tracks/Busses" "Unmute/Unsolo").