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.
AAAB1nicJY5HjsUwDEPpnjq5sAP44BIy5NfmgWoUxztelLe8wNuliG1i4pp14plJioAnX5lAdjhKgGULsNED1TECw/H55+shaFBlUGXQVfbo0YWDJtXUK4Gq2+IryTQ5n9ZA0R50kfTtB5ZDgTpXqLJ+8LZEoOarK0tSlqS9KlWl/qzZughc1g1ngOUeKIYtkA0j8BkeG7Y+ggZZBlkGUIno0YWDXWpX7wxk3RZbt0xvq4YjULTXddH07QeWQ4E2rlBV/eDtGYGSrU1ZbmW5tXdIHVL/NLTKIw==