Allow widgets to choose not to propagate actions

Allow widgets to choose not to propagate actions. This is important for
widgets that themselves trigger actions.

Note that this change will cause problems with any existing
5.1.8-prerelease plugins that call `invokeActions()`.

core/modules/widgets/button.js

@@ -63,7 +63,7 @@ ButtonWidget.prototype.render = function(parent,nextSibling) {
 	// Add a click event handler
 	domNode.addEventListener("click",function (event) {
 		var handled = false;
-		if(self.invokeActions(event)) {
+		if(self.invokeActions(this,event)) {
 			handled = true;
 		}
 		if(self.to) {
@@ -94,6 +94,13 @@ ButtonWidget.prototype.render = function(parent,nextSibling) {
 	this.domNodes.push(domNode);
 };
 
+/*
+We don't allow actions to propagate because we trigger actions ourselves
+*/
+ButtonWidget.prototype.allowActionPropagation = function() {
+	return false;
+};
+
 ButtonWidget.prototype.getBoundingClientRect = function() {
 	return this.domNodes[0].getBoundingClientRect();
 }

core/modules/widgets/widget.js

@@ -476,29 +476,30 @@ Widget.prototype.removeChildDomNodes = function() {
 };
 
 /*
-Invoke any action widgets that are descendants of this widget.
+Invoke the action widgets that are descendents of the current widget.
 */
-Widget.prototype.invokeActions = function(event) {
-	return this.invokeActionCall(this,event);
-};
-
-/*
-Recursively search through descendants, invoking all actions encountered.
-*/
-Widget.prototype.invokeActionCall = function(here,event) {
+Widget.prototype.invokeActions = function(triggeringWidget,event) {
 	var handled = false;
-	for(var t=0; t<here.children.length; t++) {
-		var child = here.children[t];
-		if(child.invokeAction && child.invokeAction(this,event)) {
+	// For each child widget
+	for(var t=0; t<this.children.length; t++) {
+		var child = this.children[t];
+		// Invoke the child if it is an action widget
+		if(child.invokeAction && child.invokeAction(triggeringWidget,event)) {
 			handled = true;
 		}
-		if(this.invokeActionCall(child,event)) {
+		// Propagate through through the child if it permits it
+		if(child.allowActionPropagation() && child.invokeActions(triggeringWidget,event)) {
 			handled = true;
 		}
 	}
 	return handled;
 };
 
+
+Widget.prototype.allowActionPropagation = function() {
+	return true;
+};
+
 exports.widget = Widget;
 
 })();