Howdy,
Does anyone know if there's a way to scrub the timeline w/o updating the animated objects?
If I use the MMB (which apparently has to be grabbed from its location, you can't simply click somewhere on the timeline and make it snap there) only the selected objects will be taken into consideration i.e. will not be updated.

I was going to say ‘switch cook mode to on mouse-up’ but that doesn't seem to apply to the playbar for some reason. I guess you are stuck typing the frame number for now.

Where does it apply though? Scrubbing in the animation editor, both graph and dopesheet, seems to me no difference.
And even if it worked, as I understand it, I don't get how it would help me. Are you sure you understood what I'm after?
I guess it's gifs time.

edit: Just to be sure everything's clear, because it'll be a while until I get the chance to make gifs: the feature that I'm addressing is working fine for one or more selected animated object. It doesn't work for other unselected animated objects in the scene.

inhiding
Scrubbing in the animation editor, both graph and dopesheet, seems to me no difference.

Oh, I thought you meant the playbar. I never use those.

The playbar is what I had in mind.
I'll post gifs later, we're not making any progress here.

Hi Jason (are you Jason? Have I found you? )
Attached you'll see three gifs.

The 1st shows a simple animation of the two objects, while scrubbing the timeline, normally, with LMB.
The 2nd shows what's happening while scrubbing the timeline with MMB. Works as expected - they keep their transf. values.
The 3rd one shows the issue I was trying to explain - the deselected animated object does not obey the rule “while scrubbing with MMB, stay put”.

There are practical reasons for wanting all the animated objects in the scene to keep their transf. while MMB-ing the timeline which I won't describe in detail unless requested, but I'll just mention posing and animation of a character.

Is this what you initially understood I was referring to? I will re-read your replies if that's the case.

Aren't you moving the keyframe when you drag like that in the middle one?

Well, the green markers are staying put, so the answer is no. Otherwise I'm not sure what you mean. Is it related to the orange line that appears? I don't know what that is.

I've attached two more gifs, for any potential animators out there and a dev that might follow this, to showcase a practical usage of this feature.

The 1st shows an amazing animation I've made in just a few minutes. Going from crouched @ frame 1 to jump extension @ frame 5.

Now, if I was an animator (the 2nd gif description), I would of course want to delay those feet lifting off the ground, so I select the rig ctrls I'm interested in (marked with white color in the viewport), keep the time at 0 and MMB on the frame I want (3 in this case) and place a key for the selected ctrls at frame 3. The fact that the non-selected ctrls stay unmoved allows me to change my mind regarding the specific ctrls I want to key, without being penalized with going back to frame 1 and selecting everything I think I will need.