QTfrontend: Fix flickering and bad offset of control config popup
If you opened the pop-up to change a key, there was a very short flicker at the left side
and the pop-up had a bad offset which sometimes caused entries to be out of screen bounds.
AAAB1nicLY9bjsMgDEUNNjhp2syGg8TCQR0f6M+R7ftIqE2apGZNrHkTb6XJ+cTtfuJ2PXE7nrjZ/M5uU6ZUpsrkgV6YytTf6rOwLlRulUQiEWnbyFQ5lhA0IEJWqVISOXw9M6UNB2FJmL/EZMcy5oUlGIIhKH1KTIkVbgsVn/OnUfoa8ZjXiO8eTAeTB/rJdA79rT4K6wLPAsdIJIyWhUyVYwnhCshN9qLqIvEOX38zfTYchOWD+Y/YvWMZ88ISDMEQlD4lpsQKt4WKj2dR+g9qCctS