Here's a feature I always wanted: I have two buffers opened side-by-side and I'd like to be able to start an incremental search in one of those buffers, but in a way which highlights results in both buffers.
This would be extra useful to make sure I didn't make a typo - it's sometimes hard for me to be sure just by looking at the text. Alternatively, something like idle highlight but for all visible buffers would work as well.
Is there a package for that? Can it be done?