Implement somewhat working drag & drop and improve render memoization

src/useMergedRefs.ts

@@ -0,0 +1,16 @@
+import { MutableRefObject, RefCallback, useCallback } from "react";
+
+export const useMergedRefs = <T>(
+  ...refs: (MutableRefObject<T | null> | RefCallback<T | null>)[]
+): RefCallback<T | null> =>
+  useCallback(
+    (value) =>
+      refs.forEach((ref) => {
+        if (typeof ref === "function") {
+          ref(value);
+        } else {
+          ref.current = value;
+        }
+      }),
+    refs
+  );