Bug: System tray icon never appears after an app update on Windows 10 (GUID-identified icon stays bound to the old package path) #19100

Description

With "Show system tray icon" enabled, Files shows no tray icon on Windows 10 once the package has been updated.

The icon is registered with NIF_GUID (684F2832-AC2B-4630-98C2-73D6AEBD4004 for sideload Stable, ...4002 for sideload Preview). Windows 10 keeps GUID-identified notification icons in the IconStreams blob (HKCU\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify) together with the full path of the executable that first registered them, and in practice refuses NIM_ADD for that GUID from a different path. MSIX install paths contain the version (...\WindowsApps\Files_4.3.0.0_x64__1y0xx7n9077q4\Files.exe), so every update changes the path.

Evidence from an affected machine:

• The IconStreams record for GUID ...4004 was bound to ...\WindowsApps\Files_4.1.3.0_x64__1y0xx7n9077q4\Files.exe (the Preview GUID ...4002 record likewise still points at FilesPreview_4.2.0.0).
• With Files 4.3.0 running and ShowSystemTrayIcon = true, no icon appeared, neither in the notification area nor in the overflow, and Shell_NotifyIconGetRect for the GUID returned E_FAIL.
• After stopping Explorer and changing only the path in that record to the 4.3.0 install path, the icon appeared on the next start of Files and Shell_NotifyIconGetRect succeeded.

Current code (src/Files.Storage/Windows/Managers/SystemTrayManager.cs, src/Files.App.Server/Tray/SystemTrayIcon.cs) still adds the icon with NIF_GUID and simply returns false if NIM_ADD fails, so the next update will break it again.

Steps To Reproduce

1. On Windows 10, install a sideload build, enable "Show system tray icon" and let the icon appear once.
2. Update Files to a newer version (the install path changes).
3. Start Files: no tray icon is shown.

Suggested fix

If NIM_ADD with NIF_GUID fails, fall back to a window-handle + uID icon without NIF_GUID; or avoid NIF_GUID for packaged builds on Windows 10.

Files Version

4.3.0.0 (Stable, sideload); the same pattern is visible for Preview.

Windows Version

10.0.19045.7417