@
Chris_Snow - my
Open with for Sigil (shift+'S') stopped working shortly after Kovid gave calibre it's own
Open With in Version 2.21. I cursed, but soon discovered it was it was entirely my own doing. I had upgraded Sigil to a later version - and unwittingly from 32 to 64 bit so the path was wrong in the PI customisation.
But I took the opportunity of trying the new built in Open With, it works more like an OS Open With (but better, than Windows at least), where you configure each file type (format) separately. Below you see my Open With list for ePUBs, all I had to do was to point calibre at the relevant programs.
The built in version doesn't suit everyone because there's no "Open With" toolbar button to click. But if you're not into clicking toolbar icons it's worth a try.
Some folks use the
Open with PI as an arbitrary program launcher, but I discovered that I wasn't doing anything with the
Open with PI that I couldn't do just as readily with the built in
Open With so I removed the PI.. And that eliminated my confusion of having
Open With and
Open with choices in Preferences->Keyboard. A single letter case switch is far too subtle for me
BR