Experiment: add support for distinguishing hover & click events

src/interactions/pointer.js

@@ -126,7 +126,7 @@ function pointerK(kx, ky, {x, y, px, py, maxRadius = 40, channels, render, ...op
 
         // Dispatch the value. When simultaneously exiting this facet and
         // entering a new one, prioritize the entering facet.
-        if (!(i == null && facetState?.size > 1)) context.dispatchValue(i == null ? null : data[i]);
+        if (!(i == null && facetState?.size > 1)) context.dispatchValue(i == null ? null : data[i], s);
         return r;
       }
 

src/plot.js

@@ -171,11 +171,21 @@ export function plot(options = {}) {
     return {...state, channels: {...state.channels, ...facetState?.channels}};
   };
 
+  class StickyEvent extends Event {
+    constructor(type, options) {
+      super(type, options);
+      this.sticky = options.sticky;
+    }
+  }
+
+  context.stickyState = undefined;
+
   // Allows e.g. the pointer transform to support viewof.
-  context.dispatchValue = (value) => {
-    if (figure.value === value) return;
+  context.dispatchValue = (value, sticky) => {
+    if (figure.value === value && context.stickyState === sticky) return;
     figure.value = value;
-    figure.dispatchEvent(new Event("input", {bubbles: true}));
+    context.stickyState = sticky;
+    figure.dispatchEvent(new StickyEvent("input", {bubbles: true, sticky}));
   };
 
   // Reinitialize; for deriving channels dependent on other channels.