Add mouse safe area for when moving between contextual submenus

app/components/ContextMenu/MouseSafeArea.tsx

@@ -0,0 +1,66 @@
+import * as React from "react";
+import { useMousePosition } from "~/hooks/useMousePosition";
+
+type Positions = {
+  /* Sub-menu x */
+  x: number;
+  /* Sub-menu y */
+  y: number;
+  /* Sub-menu height */
+  h: number;
+  /* Sub-menu width */
+  w: number;
+  /* Mouse x */
+  mouseX: number;
+  /* Mouse y */
+  mouseY: number;
+};
+
+/**
+ * Component to cover the area between the mouse cursor and the sub-menu, to
+ * allow moving cursor to lower parts of sub-menu without the sub-menu
+ * disappearing.
+ */
+export default function MouseSafeArea(props: {
+  parentRef: React.RefObject<HTMLElement | null>;
+}) {
+  const { x = 0, y = 0, height: h = 0, width: w = 0 } =
+    props.parentRef.current?.getBoundingClientRect() || {};
+  const [mouseX, mouseY] = useMousePosition();
+  const positions = { x, y, h, w, mouseX, mouseY };
+
+  return (
+    <div
+      style={{
+        position: "absolute",
+        top: 0,
+        // backgroundColor: "rgba(255,0,0,0.1)", // Uncomment to debug
+        right: getRight(positions),
+        left: getLeft(positions),
+        height: h,
+        width: getWidth(positions),
+        clipPath: getClipPath(positions),
+      }}
+    />
+  );
+}
+
+const getLeft = ({ x, mouseX }: Positions) =>
+  mouseX > x ? undefined : -Math.max(x - mouseX, 10) + "px";
+
+const getRight = ({ x, w, mouseX }: Positions) =>
+  mouseX > x ? -Math.max(mouseX - (x + w), 10) + "px" : undefined;
+
+const getWidth = ({ x, w, mouseX }: Positions) =>
+  mouseX > x
+    ? Math.max(mouseX - (x + w), 10) + "px"
+    : Math.max(x - mouseX, 10) + "px";
+
+const getClipPath = ({ x, y, h, mouseX, mouseY }: Positions) =>
+  mouseX > x
+    ? `polygon(0% 0%, 0% 100%, 100% ${(100 * (mouseY - y)) / h - 10}%, 100% ${
+        (100 * (mouseY - y)) / h + 5
+      }%)`
+    : `polygon(100% 0%, 0% ${(100 * (mouseY - y)) / h - 10}%, 0% ${
+        (100 * (mouseY - y)) / h + 5
+      }%, 100% 100%)`;

app/components/ContextMenu/Template.tsx

@@ -21,6 +21,7 @@ import {
 } from "~/types";
 import Header from "./Header";
 import MenuItem, { MenuAnchor } from "./MenuItem";
+import MouseSafeArea from "./MouseSafeArea";
 import Separator from "./Separator";
 import ContextMenu from ".";
 
@@ -59,6 +60,7 @@ const Submenu = React.forwardRef(
           )}
         </MenuButton>
         <ContextMenu {...menu} aria-label={t("Submenu")}>
+          <MouseSafeArea parentRef={menu.unstable_popoverRef} />
           <Template {...menu} items={templateItems} />
         </ContextMenu>
       </>

app/hooks/useMousePosition.ts

@@ -0,0 +1,31 @@
+import { throttle } from "lodash";
+import * as React from "react";
+
+/**
+ * Mouse position as a tuple of [x, y]
+ */
+type MousePosition = [number, number];
+
+/**
+ * Hook to get the current mouse position
+ *
+ * @returns Mouse position as a tuple of [x, y]
+ */
+export const useMousePosition = () => {
+  const [mousePosition, setMousePosition] = React.useState<MousePosition>([
+    0,
+    0,
+  ]);
+
+  const updateMousePosition = throttle((ev: MouseEvent) => {
+    setMousePosition([ev.clientX, ev.clientY]);
+  }, 200);
+
+  React.useEffect(() => {
+    window.addEventListener("mousemove", updateMousePosition);
+
+    return () => window.removeEventListener("mousemove", updateMousePosition);
+  }, []);
+
+  return mousePosition;
+};