I noticed something here.
When one MIDI editor per project is active, and these options enabled:
Active MIDI item follows selection changes in arrange view
Selection is linked to editability
(Optionally) Selection is linked to visibility
Then if you zoom out enough to see multiple items, zoom is preserved as you select different items for editing... that is UNTIL you select an item that is outside the MIDI editor viewport, which Reaper then messes up and zooms into the selected item, instead of just
scrolling to it!
Another problem is that depending on item selection, and probably also contributing to the problem here: Reaper simply truncates the MIDI editor ruler - for example, if you have a bunch of items, and you select items starting from bar 20, you can never scroll back to bar 1 in MIDI editor after that! This "ruler truncation" also happens if you use horizontal scrolling action - even if the ruler wasn't truncated automatically when selecting a different set of items! That's pretty bad (and also not something that happens with the main arrange view - so why can't MIDI editor behave the same?)... Also, this truncation happens regardless of MIDI editor timebase - it should NEVER happen in "project beats" or "project time" timebases - they are supposed to show the whole project's timeline, just like they do in the arrange view!
Seems like a relatively simple thing to fix -
just SCROLL to the items, never ZOOM, and while at it, also NEVER truncate the ruler! After all, arrange view has a stable zoom level as last one used is remembered, and even when selecting different items from Project Bay, it just scrolls to the one you selected, instead of re-zooming into it!
Here's a GIF explaining the above happenings. I hope schwa sees this and comments (right-click->"View image" to see fullsize)...
