This could be argued as a ‘feature request’, as expand-on-drop isn’t by definition “wrong” – it could be considered an intended behavior by some.
But it’s annoying to me.
It also happens when copy/pasting.
Is not limited to only Projects; I often get unprefixed Parents that auto-expand when dropped (or pasted). But sometimes they don’t. I don’t know why. I had thought it was actually the Pane re-applying the filter and auto-expanding-to-show-matches, but testing doesn’t bear that out. Having said that, I have also encountered situations where auto-expand-to-show-matches doesn’t correctly expand (leaving some items hidden). So maybe my hunch is actually right but I can’t prove it because of an overlapping bug…
As with anything automatic, having zero control can be aggravating. Often, I tweak a filter (like to show completes) in a mostly-collapsed Pane and the whole Outline auto-expands, completely losing my place.
I dream of a global setting that enables/disables auto expand (for all reasons, including copy/paste and applying filters). That could be paired with a per-pane button/command to manually trigger an auto-expand event. That button would be nice to have even for people who leave auto-expand turned on, since it could be used to “re-expand” a Pane after manually collapsing to hide some matches. Today, I will sometimes quickly toggle a filter off then back on, just to achieve that effect.