Added th-editing-tiddler hook in handleEditTiddlerEvent. A plugin can use the hook to return false and prevent editing or provide alternative editing options. (#2901)

core/modules/widgets/navigator.js

@@ -211,6 +211,10 @@ NavigatorWidget.prototype.handleCloseOtherTiddlersEvent = function(event) {
 
 // Place a tiddler in edit mode
 NavigatorWidget.prototype.handleEditTiddlerEvent = function(event) {
+	var editTiddler = $tw.hooks.invokeHook("th-editing-tiddler",event);
+	if(!editTiddler) {
+		return false;
+	}
 	var self = this;
 	function isUnmodifiedShadow(title) {
 		return self.wiki.isShadowTiddler(title) && !self.wiki.tiddlerExists(title);