Yeah, I think it's html5/webgl builds but not necessarily the build. I think it's the browser? I use opera gx most and it pops up asking me if I want to allow mouse capture (on every capture mouse game), and same as when you press esc its the browser is what releases the cursor - thus p to pause on web. I'm not sure whats the best way to handle this in future is but I'll have to figure it out!