A few months ago on a different character I accidentally sold a T7 exalted helm with a +4 skill affix because I wasn’t fully holding down the shift button when I thought I was. Unfortunately I didn’t notice until I’d sold too many other things to be able to buy the helm back.
Today I almost sold a dagger on a different character the same way. Fortunately this time it was a unique dagger, and I caught it because I had already looked at my inventory and saw only rare and exalted items in it, so as I was selling items to the vendor I was confused for a moment where the unique item came from. Fortunately I was able to swap this item back.
I’m sure I can’t be the only person this has happened to. I don’t see a keybinding for this, so PLEASE give us a checkbox where we can disable swapping equipped items on right-click. It was a nice idea, but I have never used it, I don’t want to use it, and IMO the downsides of it being enabled far outweigh the benefits.