Make the blur-effect precision-agnostic
Right now the blur effect works only is fairly small items: normal-sized text in high-DPI is still readable, same for large text in regular DPI.
Maybe Obfuscate whould use a blurring alforithm that doesn't depend on a fixed number of pixels but on the selected zone?
E.g. it could could use linear interpolation from the borders of the selection, or from its corners maybe.