Dialog Post draw help

[Moooce]

Hi, can someone help point me in the right direction here?

I'm trying to show a dialogbox with a message that the user should wait (works)
Then when the dialog is shown with this message start a process that takes a while.
update the dialogbox to show the results.

Problem is how do I determine the dialog has been drawn for the user to read, and now I can do the processing?

I have something like the below:

INT_PTR CALLBACK DlgProc( HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam )
{
	UNREFERENCED_PARAMETER( lParam );

	switch( message )
	{
	case WM_INITDIALOG:
		SetDlgItemText( hDlg, IDC_USERMESSAGE, "Please Wait." );
		return (INT_PTR)TRUE;
	case <WM_TheDialogHasBeenDrawn>:
		// User can see the message now so we can proccess
		// do somthing that takes a while
		// show the results in IDC_USERMESSAGE
		return (INT_PTR)TRUE;
.....

Is there a Windows message I can use for WM_TheDialogHasBeenDrawn or am I barking up the wrong tree?

Thanks.

[Moooce]

Anyone?