You mentioned you might be working on a splitter. If so, here's what I'd find useful:
a splitter that supports both orientations, with a move handle.
a fixed split position unless moved by the user or code. That is, the pane sizes should be influenced by the split position rather than the other way around.
a split position property to allow the position to be persisted.
Is this something you're definitely doing, and do you have a time frame? My needs are just what is stated above:
Migrated from #8.
You mentioned you might be working on a splitter. If so, here's what I'd find useful:
Is this something you're definitely doing, and do you have a time frame? My needs are just what is stated above: