"Explode" tool only does whole bars, ignoring selection

That is to say, if you select a partial measure, the explode tool will try to apply even to the notes in the measure that you haven't selected, which generally means it will just copy a single identical note or a rest onto as many staves as there are notes in the chords you actually meant to explode.
Maybe this is intended behaviour, but if so, it should be written in the menu entry, because it's important information - one might otherwise not notice that they've overwritten a few notes of work. Also, if it's intended behaviour, it's a pretty impractical one.