Add files

src/renderer/lib/dispatcher.js

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+module.exports = {
+  dispatch,
+  dispatcher,
+  setDispatch
+}
+
+const dispatchers = {}
+let _dispatch = () => {}
+
+function setDispatch (dispatch) {
+  _dispatch = dispatch
+}
+
+function dispatch (...args) {
+  _dispatch(...args)
+}
+
+// Most DOM event handlers are trivial functions like `() => dispatch(<args>)`.
+// For these, `dispatcher(<args>)` is preferred because it memoizes the handler
+// function. This prevents React from updating the listener functions on
+// each update().
+function dispatcher (...args) {
+  const str = JSON.stringify(args)
+  let handler = dispatchers[str]
+  if (!handler) {
+    handler = dispatchers[str] = e => {
+      // Do not propagate click to elements below the button
+      e.stopPropagation()
+
+      if (e.currentTarget.classList.contains('disabled')) {
+        // Ignore clicks on disabled elements
+        return
+      }
+
+      dispatch(...args)
+    }
+  }
+  return handler
+}