allow to explicit register callbacks for the broadcasted push messages

egw.registerPush(Function)

The callback should have a bound context, if it requires one!

api/js/jsapi/egw_jsonq.js

@@ -20,6 +20,13 @@ egw.extend('jsonq', egw.MODULE_GLOBAL, function()
 {
 	"use strict";
 
+	/**
+	 * Explicit registered push callbacks
+	 *
+	 * @type {Function[]}
+	 */
+	let push_callbacks = [];
+
 	/**
 	 * Queued json requests (objects with attributes menuaction, parameters, context, callback, sender and callbeforesend)
 	 *
@@ -149,6 +156,34 @@ egw.extend('jsonq', egw.MODULE_GLOBAL, function()
 				}, 100);
 			}
 			return uid;
+		},
+
+		/**
+		 * Register a callback to receive push broadcasts eg. in a popup or iframe
+		 *
+		 * It's also used internally by egw_message's push method to dispatch to the registered callbacks.
+		 *
+		 * @param {Function|PushData} data callback (with bound context) or PushData to dispatch to callbacks
+		 */
+		registerPush: function(data)
+		{
+			if (typeof data === "function")
+			{
+				push_callbacks.push(data);
+			}
+			else
+			{
+				for (let n in push_callbacks)
+				{
+					try {
+						push_callbacks[n].call(this, data);
+					}
+					// if we get an exception, we assume the callback is no longer available and remove it
+					catch (ex) {
+						push_callbacks.splice(n, 1);
+					}
+				}
+			}
 		}
 
 	};

api/js/jsapi/egw_message.js

@@ -459,6 +459,9 @@ egw.extend('message', egw.MODULE_WND_LOCAL, function(_app, _wnd)
 					app_obj.push(pushData);
 				}
 			}
+
+			// call the global registered push callbacks
+			this.registerPush(pushData);
 		}
 	};