It should be possible to add multiple one-time only filters but have only one of them at most active at a time. That allows, for example, to add two instances of the “Crop Source” filter with different parameters before starting to split a track, and then just enable the correct filter for one of multiple possible crop regions without having to reenter parameters all the time.
Also the discoverability of the only-once behavior would seem to be better if the other filter is flipped off when the new filter is added/selected. I feel that this would be more obvious in conveying the restriction than ignoring the “add filter” button.
Well, this helps and I’ll readily admit that it didn’t occur to me. It does feel like a workaround and may lead to a proliferation of presets that may only be relevent for a particular source video. Personally I prefer it when obvious workflows work, even if there is a comparatively manageable workaround that skilled users might think of.
I didn’t suggest that your idea is bad.
In fact, a few times in the past I had to do almost the same thing you describe in your post.
For me, the obvious workflow was to use this presets method. Creating a preset doesn’t take much more time than adding a second Crop: Source filter with different settings in the filters list.
And to avoid cluttering the presets list with one-time presets, when the project is done I simply delete them.
