Issue: Incorrect Start Menu rendering in Coherence Mode when taskbar auto-hide is enabled

Hello,

I would like to report a rendering issue related to Coherence Mode.

The attached screenshot was taken while I was adjusting the Windows taskbar color to better match the macOS wallpaper color.

When the Windows taskbar is set to auto-hide and Coherence Mode is enabled, opening the Start Menu causes it to overlap with the taskbar area. In addition, the background color around the Start Menu -- especially the area where the drop shadow should appear -- is rendered incorrectly. The color does not match either the macOS background or the Windows UI theme and appears visually inconsistent.

Please note that the overall dark color tone in the screenshot is intentional and based on my personal preference. The issue described above is independent of the selected color theme.

Steps to reproduce:

1. Enable Coherence Mode.
   
   
2. In Windows, set the taskbar to auto-hide.
   
   
3. Open the Start Menu.
   

Environment details:

Mac:
MacBook Pro 16-inch (2021)
Apple M1 Max
32 GB RAM
macOS Tahoe 26.3

Windows:
Windows 11 Pro (Japanese)
Version: 24H2
Build: 26100.7840

Parallels Desktop:
Parallels Desktop 26 for Mac
Version: 26.2.2 (57373)

Thank you for your support. Please let me know if additional information or logs are required.