New source found from dndbeyond.com

ddb_main/node_modules/@dndbeyond/ttui/components/Dialog/Dialog.tsx

@@ -15,6 +15,7 @@ export interface DialogProps extends HTMLAttributes<HTMLDialogElement> {
   open: boolean;
   onClose: (e?: MouseEvent) => void;
   modal?: boolean;
+  onBackdropClick?: () => void;
 }
 
 export const Dialog: React.FC<DialogProps> = ({
@@ -23,6 +24,7 @@ export const Dialog: React.FC<DialogProps> = ({
   modal,
   children,
   className,
+  onBackdropClick,
   ...props
 }) => {
   const dialogRef = useRef<HTMLDialogElement>(null);
@@ -46,7 +48,10 @@ export const Dialog: React.FC<DialogProps> = ({
       rect.left <= e.clientX &&
       e.clientX <= rect.left + rect.width;
 
-    if (!isClickInDialog) handleClose();
+    if (!isClickInDialog) {
+      onBackdropClick?.();
+      handleClose();
+    }
   };
 
   const handleEsc = (e: KeyboardEvent) => {