a collapsible source panel so that you can quickly view the source citation
This I like too.
I almost always, when finding something in the index, go straight to the original image and bypass the transcription. Unfortunately the source citation is on the transcription page, and you cannot always extrapolate it from the original image, because not every page shows the folio number. So this is very useful.
And I vastly prefer Ancestry's policy of adding alternative readings to the index. Yes, I know the rules about transcribing, but adding something to the
index does not compromise the
transcription. The index is purely a finding aid, and it's no use at all if you can't find someone because a mistake was made on the form. We have the opportunity to make our own judgements by viewing the original - but only if we can find it.