Felipe Lema authored Jun 20, 2021 and Dmitry Kazakov committed Jun 29, 2021

- detail semantics when "cancelling filter manager": either cancel
running stroke or cancel the dialog as a whole
- delay deletion / freeing-resources-of `filterDialog` to prevent Qt
internals to modify/read this dangling object-pointer
- the above was the cause of the segmentation fault reported in #438853
(specifically, Qt's accesibility-update-functions were running due to a
checkbox state update _after_ `d->filterDialog` had been deleted