Weird editing behavior in AFP

### Bug Summary
The interactions between the controls and the sample view in AFP are quite weird and unintuitive.

Some of these are shown in the video below:
* If you adjust the amplitude the sample section shown in the sample view changes/jumps.
* If you interact the with sample view, e.g. clicking and pulling it, then the controls also change.

https://github.com/LMMS/lmms/assets/9293269/c324ab32-61e0-4400-b24c-3c6aebd63d74

#### Steps to reproduce
Interact with AFP. ;)

#### Expected behavior
Zooming and changing the controls should be separate operations that do not affect each other.

Start by reproducing the AFP interactions described in the issue and reviewing the linked video. Trace how the AFP controls and sample view respond to amplitude changes and dragging. Done means zooming or changing controls no longer changes the other operation unexpectedly.

Written by the indexing model from the issue text.