Exporting the Dialog Box Procedure

Because this dialog box procedure is called from outside the program, it must be included in the EXPORTS section of the module definition file:

EXPORTS WndProc

AboutDlgProc

This is the easiest part of the job but also the easiest to forget. I forget to export the dialog box procedure about one time in four. Often the function will seem to work (more or less), but because it's not using the program's data segment, it could be altering data inside Windows' data segment. Our simple dialog box procedure doesn't reference anything in ABOUT1's data segment, so strictly speaking, exporting the function is not required. But get into the habit of exporting the function; I hope you achieve a better track record than mine.