There isn't actually a "resume game" but your "new game" seems to be the resume function. Seems your label doesn't update properly when you are in a game haha. Anyway, yeah, clicking new game actually gives me mouse control back. It is confirmed that this involves the web player losing focus either via clicking off the frame, changing tabs, or even hitting escape to bring up the menu options. Once you click the new (resume) game button, it restores mouse focus, but not before hat point, even just hitting escape to close the menu back out after interacting with it causes the focus to slip away, it seems.