Steps to reproduce

1. Enable snapping to milliseconds
2. Zoom in to see 1 ms of increment on the timeline
3. Try to trim or stretch the clip
4. Observe

OR

1. Zoom in enough to see individual stem plots
2. Slowly start to trim/untrim/stretch the clip
3. Observe

Expected behavior

No jitter. Snapping to milliseconds as well as trimming and stretching when individual stem plots are visible is nice and smooth.

Actual behavior

As you move the cursor left and right near each snapping point, both the snapping guideline and the edge of the clip are jittery:

Trimming (stretching) when individual stem plots are visible is jittery:

Audacity Version

master (clip's edge is jittery), #8806 (guidelines are introduced in this PR)

Operating system

OS independent