Make a copy of the clip onto a PIP track.

Now you have two identical tracks running together.
Make timeline positions where it will be OK to stretch the video - Not where talking or singing in close-up on screen.
Use the Power Tools Video Speed to change part of one section faster, the next sect slower.

Do all changes ONLY on one track leaving the Master Track untouched.

Now MUTE the track you changed if it messed up the sound when you speed it up, because PD will drop the sound if its too fast or slow.

You can now use the sound from the master tack and move its video off-screen

Result: Master sound with PIP video

If you can't solve the problem - Change the problem

This is a really good trick. Thank you!

Anyway my question was about making the previous clip longer and the second shorter by acting only on the trim points (supposing that both clips have been trimmed) and not on video speed.

I explain with a schema:

before:
[AAAAAAAAAAAAAAAAAAAAAA][BBBBBBBBBBB] ^

after:
[AAAAAAAAAAAAAA][BBBBBBBBBBBBBBBBBBB] ^

I simply wondered if it's possible to drag the (^) and get the result in one move. I know it's a really specific request... but just wondered if it was possible. Looks like it's not possible so, to exactly get the same result, i need to track down (A) length, adjust it, compute the difference by checking the new (A) length and apply this difference (by numerically editing the clip duration) to (B).

Only a little bit longer.

Regards. Umberto

Works well with landscape and still life.

Changing speed to slower also works well when zooming in on artwork.

Most camersa have a jerk or lurch when zooming starts and finishes.

Clip out the beigin and end portion of a zoom and then stretch the remaininder by as much as 2X

You will then have a very good zoom. Slow and stable. If you can't solve the problem - Change the problem