Int 50 Fn 0000  - Vanderaart Text Windows, Pc Thuis Shell - Open Text Win  [V]

   AX = 0000h
   ES:BX -> name string or ES:0000h if none
   CH,CL = row,column of upper left corner
   DH,DL = row,column of lower right corner

Return: AX = window handle or
       0000h if not installed
       FFFFh on error

See Also: AX=0001h,AX=0002h"TEXT WINDOWS"