In some cases, customers are seeing a black background appear when a pop-up window is present in a published application. The black background shows up behind the main application window, but does not span the entire screen.

Applications are published from a multi-session VDA running CVAD 2507 on Windows Server 2025.

This issue was not seen in earlier versions of the VDA or Windows Server.

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The black window is related to snap layouts (as seen in Windows 11 when you drag a window to the top of the screen). This is a transparent window owned by the ShellAppRuntime process. Currently, transparent windows are not supported in published applications. a

In the long term, this will be addressed when transparent window support is added in a future CVAD release, but in the short term, the current recommendation is disable the snap bar with the following registry setting on the VDA

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
EnableSnapBar DWORD 0x0