forked from CGM_Public/pretix_original
* move iframe after close-button to follow tab-order * add missing prevActiveElement * prepare focus-handling for error_message * iframe.src through prop instead of directly accessing it * do not change close button HTML-element for compatability * make all overlay elements role=dialog and modals * fix close button * fix re-opening of iframe * make error-message read out when shown * Improve handling of frame_src with frame_loading * manually focus continue or close button in alert-box * fix btn-focus in transition * Improve quantity group