[Client] Bringing up mastery page edit can lock game, requires full reload

Was setting up Team Builder and opened up mastery pages to edit. Client window was moved to the side and mastery page close button (X) was off screen. Client does not allow for the window to be moved when in mastery page so user cannot close the mastery page to continue on in client. Requires full client close and reload to fix. Simple issue, please make client window and mastery page popup movable.