INT 15 - DESQview v2.26+ - "ASSERTVIR" - CONTROL 386 SCREEN VIRTUALIZATION
AX = DE21h
BX = new state
0000h turn off
nonzero turn on
Return: BX = old state of virtualization
Notes:  this API call may be made from within a hardware interrupt handler
under DV 2.40 and 2.42, this call appears to have no effect and always
returns a nonzero value in BX which appears to be the offset within
the DV common memory segment of the caller's task object; it may
only have an effect within a hardware interrupt handler
SeeAlso: AX=DE17h

See also: 151117

15DE21 - DESQview v2.26+ - "ASSERTVIR" - CONTROL 386 SCREEN VIRTUALIZATION