How to get window handle of main dialog box

I am writing QuickWin console application and cannot figure out how to get the window handle of my main (modeless) dialog box (which I call IDD_DIALOG1).  I know how the get the handle for dialog controls (e.g. hWnd=GetWindowItem(dlg%hWnd,IDC_CONTROL)), but not for the main window.

I want this handle for when I launch a pop-up modal dialog box (from the main program - not from a callback routine), using reti=dlgmodalwithparent(dlg2,hWndParent), where hWndParent is the handle to my main dialog box.  I want to do this so my main dialog box will be disabled while the new dialog is displayed.

Any help will be appreciated.