MsgBoxAsk PROC

  Displays a graphical popup message box with Yes and No buttons.

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

Return arg: EAX = selection by user (IDYES, or IDNO)

Example:

.data
question BYTE "Would you like to open the file?",0
answer   DWORD ?

.code
      mov  eax,OFFSET question
      mov  ebx,0                       ; no caption
      call MsgBoxAsk
      cmp  answer,IDYES
      jne  next
open_file: