In an Add-On I'm working on, I procedurally generate a modest-to-large number of collections, and often end up with an outliner looks something like this:
I then often find myself tediously clicking the "collapse" arrow one-by-one on each collection, until they're all collapsed, to clean-up my view before doing further work.
Is there a fast way to do this kind of multi-collection outliner-view collapsing? Either a native / built-in or Python solution would be fine.
Hover your mouse in the outliner and hit Shift + A to expand everything, do it again to collapse everything.
This will collapse all nested collections as well, bottom to top, so everything is nice and orderly all the way down the hierarchy.
One way not mentioned in your answer is if you click on the collapse arrow and hold the mouse button down, you can drag down and it will collapse (or un-collapse) as many as you hover over, this works in many other places as well, like vectors or checkboxes.
Ah: I had looked for an option to do this before posting the question, but apparently not hard enough. First, there is a partial answer here, in that using Shift allows (un-)collapsing nested hierarchies:
Expand / Collapse all hierarchy in Outliner
And, second, the +/- numpad keys allow (un-)collapsing multiple collections, level by level. That this is so is displayed under the View sub-menu, if you right-click a collection in the Outliner (which also provides another non-keyboard-based way of collapsing multiple collections, of course).
