MsgBox PROC

  Displays a graphical popup message.

Call args:  EDX = offset of a message string
            EBX = optional offset of string for box's title. Set
                  to 0 if you want the title to be blank.

Return arg: none

Example:

.data
message BYTE "This file cannot be opened.",0

.code
      mov  eax,OFFSET message
      mov  ebx,0                       ; no caption
      call MsgBox