Pagers might not work

[peterhadlaw]

Hello cross-posting for visibility because I know aider uses prompt_toolkit under the hood.

Not sure how to reproduce this directly with prompt_toolkit but here's where it's usage is defined in aider:

• https://github.com/Aider-AI/aider/blob/4a9447d344847f1deb59746771753129629df18a/aider/commands.py#L618
• https://github.com/Aider-AI/aider/blob/main/aider/io.py#L195

I've noticed pagers are broken...

Repro path:

1. Load up aider (prompt_toolkit)
2. /run more <any sufficiently long file to scroll>
3. Scroll down a little with j
4. Scroll back up with k

Expected behavior:
The lines should just scroll up and down

Actual behavior:
The cursor skips up lines and swallows some of the lines in between

Demo: