A few ideas to improve the NLA Editor

I've been using Blender a lot recently to create short narrative animations. Blender is amazing, but I've built quite a list of gripes with the NLA Editor in particular. Here's some proposals for improvements that I think would make our lives easier.

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Key frame insertion outside of tweaked strip's action extents

Preventing a user from inserting key frames outside of the strip bounds of a tweaked strip seems counter-intuitive and I can see no good reason why this is enforced, especially with Sync Length enabled. It may not seem like a massive problem at first, as one can easily set the action extents within the sidebar, but if you're testing a cyclic animation and you're trying to find the best length for your action you may need to set the action extent end frame time after time to allow new keyframes to be inserted. It's also quite easy to assume you're inserting keyframes with auto-keyframe insertion enabled, only to realise later that none of it has been recorded because you've strayed outside the action extents. It's also quite easy to mistakenly set the strip extents, scaling the strip instead.

I just don't understand why keyframe insertion isn't allowed outside the action extents while tweaking... but you can duplicate keyframes in the action editor and place them anywhere outside the extents in the dopesheet editor.

This just seems like a mistake that's been overlooked.

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Extend NLA Strips with a hotkey / dragging the edges with mouse

This needs no explanation really. There's a scale operator, but there isn't an extend operator / shortcut as far as I can tell.

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Context.nla_tracks

There is currently no easy way to find the NLA Tracks and Strips that are currently in view in the NLA Editor - which makes any Addon or Python manipulation involving NLA elements an incredibly difficult task.

If I want to find the selected NLA Strips in the current context, I have to check every object with animation data (Not just Objects, but a whole list of types that have an animation_data property) in the scene and apply all the NLA Editor filters manually in Python, and only then will I have a list of NLA Tracks that matches my context's NLA Editor.

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Breakdown Selected NLA Strips into single action

This is not the same as baking NLA Tracks into frame-by-frame keyframes, but simply taking all the keyframes and doing the best job possible of creating a single action with them. I have written a script to do this for me and I use it a lot. It ignores blend in / out and any animation data on the strip itself (animated influence, strip time), but for 99% of cases this is not an issue.

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Create a new Action with selected channels of an existing action

Very often I find I need to split an action into parts with specific channels, for separate NLA Strips. Again, I wrote myself a script to do this and it is very useful.

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A toggle button in the header bar to Show only Tweaked NLA Strips

Often I'll find I've accidentally left some strips in tweak mode and if you have a very busy NLA Editor (as I do) it can be a pain to find the relevant strips sometimes. I would appreciate a way to filter out the NLA Tracks without any strips in tweak mode.