Fix issue 14693: TrackBar UI control doesn't reflect properties

[SimonZhao888]

Fixes #14693

Root Cause

This issue was introduced by #8060 . TrackBar does not recreate/recalculate tick marks when TickFrequency changes after a size change, causing the native control to display an outdated number of ticks.

Proposed changes

• Update DrawTicksManually() method to fix an off-by-one error where the last intermediate tick was missed.
• Override the OnSizeChanged() method to prevents tick marks from retaining their original layout after the control is resized, as the control is not redrawn.

Customer Impact

• The TrackBar UI control correctly reflects the properties.

Regression?

• Yes

Risk

• Mini

Screenshots

Before

After

14693.mp4

Test methodology

• Manually

Test environment(s)

• 11.0.100-preview.5.26227.104

Microsoft Reviewers: Open in CodeFlow

[LeafShi1]

Thanks for the fix — the off-by-one in the tick loop is real and worth fixing. A few concerns to consider before merge:

1. PR description vs. code mismatch. The description says "Override the OnSizeChanged() method...", but there is no OnSizeChanged/OnResize override in the diff. The resize scenario (issue #2 in #14693) actually appears to be fixed as a side effect of making the tick count size-independent (the native control rescales stored logical tick positions on resize). Please update the description to match the code, or clarify how the resize case is covered.

2. No regression test. Since this is a runtime-only visual bug, please add a test asserting the tick count / last-interior-tick for the repro (Max=500, TickFrequency=50) so this doesn't regress again.

See inline comments for the specifics on the tick math.