[Bug]: History stacking shifts overlay vertically with custom anchor

[esphynox]

Keyty version

Observed in the first release that included custom anchor positioning, reported on August 3, 2026 in the follow-up to #57.

macOS version

Not yet provided.

Install method

Other

Steps to reproduce

1. Open Keyty and enable history so multiple keystrokes remain visible.
2. Choose a preset anchor that demonstrates stable vertical stacking, such as top center or bottom center.
3. Switch to Custom anchor and place the overlay near the top or bottom of the screen.
4. Generate enough keystrokes for the history stack to grow.
5. Observe whether the overlay remains visually anchored in place as the history expands.

Expected behavior

When using Custom anchor, history growth should preserve the chosen vertical position consistently, just like the stable preset cases.

Actual behavior

The overlay shifts vertically as history grows when using Custom anchor. The reporter noted that only top center and bottom center appear to preserve vertical position reliably, and that this vertical behavior is not carried over to Custom anchor.

Screenshots or screen recording

Original reporter attached screenshots and a screen recording in:
#57 (comment)

Logs or crash report

None.

Additional context

This issue is split from #57 so the original feature request and the follow-up behavioral bug can be tracked independently.

[InSasquatchCountry]

All current anchor point options labeled as stable (✅) and not (❌) with respect to vertical history

❌ Top Left
✅ Top Center
❌ Top Right
❌ Center Left
❌ Center Right
❌ Bottom Left
✅ Bottom Center
❌ Bottom Right
❌ Custom