INT 2F - DESQview v2.26+ XDI - CUSTOM SUBFUNCTION, DVTXDI.COM
        AX = DE01h
        BX = 7474h
        CL = function
            00h installation check
                Return: AL = FFh
            01h get process handle
                DX = keys on Open Window menu (DL = first, DH = second)
                Return: AX = process handle or 0000h if not running
            02h (v1.3+) set TMAN handle
                DX = TMAN process handle
            03h (v1.3+) set open keys to ignore on next CL=01h call
                DX = keys on Open Window menu (DL = first, DH = second)
Return: BX = 4F4Bh ("OK")
        DL destroyed
Note:   DVTXDI is distributed as part of the shareware products DVTree (DOS
         shell/DESQview process manager) and DVTMAN by Mike Weaver