In my current writing approach, I have a lot of structured custom meta-data about my individual documents – 15-20 fields worth. I do recognize it verges on treating Scrivener like a database, but it’s an important component of how I work. In any case, including all of these as columns in the outliner leads to an outline that’s much too wide. It looks, in fact, like a spreadsheet, which is just what I want it to do. So it would be useful if it had this one spreadsheet capability: the ability to select a column and “freeze” it, so that this column and those to its left stay put, and all the columns to the right can scroll left-right. Spreadsheets proper implement an up-down freeze as well as left-right, but for me, left-right is fine.
One possible implementation is for a user to first give focus to a specific outliner column (for example by editing a cell), then choose a menu option or button that would freeze that column and all those to its left. Any change to column ordering or which columns were displayed would “unfreeze” everything, I would think.
As a software developer myself, I will scrupulously avoid telling you that I think this feature is “easy”! It would, however, be highly beneficial to my writing workflow. Thanks for considering it.