Checking flags of the thread desktop to determine whether virtual desktop is on is unreliable. For example, CEF applications create their own desktop and so is_virtual_desktop() could incorrectly report that virtual desktop is off.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55810
-- v2: server: inherit DF_WINE_CREATE_DESKTOP when creating a non-root desktop.