Pointer enter leave events

js/lib/widget.js

@@ -177,6 +177,7 @@ export class RemoteFrameBufferView extends DOMWidgetView {
     // Defines how the widget gets rendered into the DOM
     render() {
         var that = this;
+        console.log("We cooking now bro")
 
         // Create a stub element that can grab focus
         this.focus_el = document.createElement("a");
@@ -264,6 +265,16 @@ export class RemoteFrameBufferView extends DOMWidgetView {
             let event = create_pointer_event(that.img, e, that._pointers, 'pointer_move');
             that.send_throttled(event, 20);
         });
+        this.img.addEventListener('pointerenter', function (e) {
+            // TODO: Do we want to edit this._pointers?
+            let event = create_pointer_event(that.img, e, {[e.pointerId]:  e}, 'pointer_enter');
+            that.send(event);
+        });
+        this.img.addEventListener('pointerleave', function (e) {
+            // TODO: Do we want to edit this._pointers?
+            let event = create_pointer_event(that.img, e, {[e.pointerId]:  e}, 'pointer_leave');
+            that.send(event);
+        });
 
         // Click events are not pointer events. Not sure if we need click events. It seems to make
         // less sense, because the img is just a single element. Only double-click for now.

jupyter_rfb/events.py

@@ -40,6 +40,14 @@
   This event has the same keys as the pointer down event.
   This event is throttled.
 
+* **pointer_enter**: emitted when the user moves a pointer into the
+  boundary of the widget.
+  This event has no additional keys.
+
+* **pointer_leave**: emitted when the user moves a pointer out of the
+  boundary of the widget.
+  This event has no additional keys.
+
 * **double_click**: emitted on a double-click.
   This event looks like a pointer event, but without the touches.