Catch deselect event with CEP extension

I try for some time to catch the (deselect) event on (canvas or stage) I don't know the exactly name for that area.
I made a panel what send the psd file to one endpoint to parse all selected layers from photoshop. But I have a problem (a small bug) I don't know how to catch the (deselect) action on layers. When I select all layers from photoshop it show in panel a message "you have selected 2 layers" but when I click on (canvas/stage) all layers should be deselect but my panel can't reset the message because I can't catch that event.

Demo deselect event: https://www.loom.com/share/7cf05d721c7b49219354b9dd9e42ffca?focus_title=1&muted=1