Screen capture using mouse doesn't work when using mouse_follows_focus on

[gservat]

I'm using Xnip to take screenshots (though I suspect this would happen with any screenshot app) and when I have mouse_follows_focus on, I start a screen capture and I lose control of the mouse pointer. It's just stuck to the dead centre of the window. If I disable mouse_follows_focus, then it works fine and I can screen capture OK.

Any suggestions? I'd like to keep mouse_follows_focus on if I can as it's handy when I'm switching between displays/spaces, but I also take screenshots so I'll have to keep it disabled for now.