I wouldn't mind this.

I'm used to copy-paste but I wouldn't bother changing this for a new feature which is also useful.

Side note. There needs to be a way to put those time stretched keys back on actual frames if you must keep doing that. It causes a lot of problems down the line.

What about a bounding box for the keyframes? That replicates a typical and obvious use case, communicates a clear mode, and allows for even more scaling options (center based).

The bounding box could be constant or a separate mode triggered by a command (Cmd T for transform?). Yes if you’re a constant opt dragger, it’s an extra step but you get more flexibility.

Would it be weird if Opt+Drag worked for duplicating a single keyframe, but when used for multiple keys you would hold Opt and drag from in between keys and a new, subtle UI element would pop up indicating that there will be a duplicate created? Something subtle like th plus icon that gets added to a folder when duplicating in Explorer and Finder.
Or maybe the selected keys would be highlighted in a new way, but only while Opt is held and the mouse is within the bounds of the selects keys, but not over one of them.

I am someone who uses the time stretch option with some frequency and I'd be perfectly fine if that moved to control/command instead of alt/opt. Sure, it'll be annoying for a bit, but I'll get used to it. And, heck, roving keyframes (ctrl+clicking) kinda feel like time stretching in a way, so it fits pretty well.
Copying keyframes while holding alt is something I can totally get behind - especially if it works on multiple layers simultaneously.

Why not command-option? Is that used?

In my view, preferences to allow users to disable new behaviours are usually a good idea (see the backlash to the new Home button, for example). Disrupting muscle memory isn't great, but it isn't the end of the world, especially if it's something less than fundamental and adds a really useful new feature.

I use Option-drag to scale keyframes quite often. Looking at current modifier combo's on keyframes, I think the one I'd miss the least is Cmd/Ctrl + Option clicking (which currently toggles Hold interpolation). Personally, I'd add a new key command for Toggle Hold Keyframe - HH. We're all using TT and UU all the time, why not use a few more double-tap keys? Then have the Cmd/Ctrl + Option drag do the duplicating. Or if people want the duplicate with Option-drag, use Cmd + Option drag for the scaling.

I also want to say that adding an option to drag keyframes to duplicate them 1. Needs to work with keyframes on multiple layers, and 2. Is not sufficient on it's own - we also need the ability to copy and paste keyframes from multiple layers with keyboard commands. Because dragging is not always easy to do with precision, for example if working in long duration comps on a smaller monitor. Pasting multiple layer keyframes to the CTI is, I would say, more important than being able to drag-duplicate them. And it should not require any more than the standard Cmd-C and Cmd-V. I was teaching 3rd year students recently and they find the existing behaviour (layers copying and pasting) bizarre - it goes against the expectations that the rest of AE's behaviours (which are more contextual, based on selection) actually engender.

Personally I prefer it as/is

We were recently evaluating part of this request, to duplicate keyframes by holding the Alt/Option key and dragging. This is something we'd love to add to After Effects. But we've run into a couple of issues.

As mentioned in the video, Alt/Option + dragging keyframes is currently occupied by the time-stretch keyframes behavior. The video suggests changing that behavior to use the Control/Command key + dragging, however that begins to get fuzzy because Control/Command + _clicking_ on a keyframe changes its interpolation to Continuous Bezier; there's a lot of opportunity here for accidental clicks.

A related problem is muscle memory. Any time we change a mouse or keyboard input behavior, we get negative reactions from our user community. The video tends to dismiss the need for time-stretching keyframes, but I both disagree with that, and want to emphasize that changing muscle memory is very disruptive.

Another complication is that Alt/Option + dragging on a layer's in/out points will time-stretch the layer. (This was added in recently, in After Effects 16.0, but we used time-stretching keyframes as the model for which keyboard shortcut to use.) If we change the meaning of Alt/Option + dragging keyframes, we may need to align other behavior as well, breaking more muscle memory.

Regardless, we agree that the existing convention of Alt/Option + drag to copy is a desirable feature for After Effects (for both keyframes and other types of objects, but one thing at a time). We discussed what other keyboard modifiers the time-stretch keyframe behavior could be moved to, but we could not find an obvious answer because After Effects is already heavily loaded with modifier key + mouse click/drag behaviors. Even something as simple as adding the Shift key would interfere with snapping behaviors.

Given those complications, how would you suggest the behaviors of clicking and dragging keyframes in After Effects be adapted?

- What modifier key + click/drag combos would you like to see?
- How do you feel about disrupting muscle memory, for both yourself and other artists?
- Do you feel a preference or UI option would be needed to allow users to enable/disable the new behaviors and return to prior muscle memory?

We will continue discussing this internally. Your opinions will help shape the conversation.

This is a fantastic idea and I would love to see this feature it would make my workflow so much faster!

I LOVE this. Even though I have already set a keyboard shortcut for reversing keyframes, I think having that functionality that Sander is describing here built into AE would be a huge improvement.

How many times have I wanted to do this!!!

But then how would we option+drag to stretch/space out keyframe groups in the timeline?