auto select web preview port

mix/HttpServer.cpp

@@ -21,6 +21,7 @@
  */
 
 #include <memory>
+#include <random>
 #include <QTcpSocket>
 #include "HttpServer.h"
 
@@ -106,8 +107,18 @@ void HttpServer::updateListening()
 	if (this->isListening())
 		this->close();
 
-	if (!m_listen || QTcpServer::listen(QHostAddress::LocalHost, m_port))
+	if (!m_listen)
 		return;
+
+	if (!QTcpServer::listen(QHostAddress::LocalHost, m_port))
+		errorStringChanged();
+
+	if (m_port != QTcpServer::serverPort())
+	{
+		m_port = QTcpServer::serverPort();
+		emit portChanged(m_port);
+		emit urlChanged(url());
+	}
 }
 
 void HttpServer::incomingConnection(qintptr _socket)

mix/HttpServer.h

@@ -100,7 +100,7 @@ protected:
 
 signals:
 	void clientConnected(HttpRequest* _request);
-	void errorStringChanged(QString const& _errorString);
+	void errorStringChanged();
 	void urlChanged(QUrl const& _url);
 	void portChanged(int _port);
 	void listenChanged(bool _listen);

mix/qml/WebPreview.qml

@@ -150,7 +150,7 @@ Item {
 		id: httpServer
 		listen: true
 		accept: true
-		port: 8893
+		//port: 8893
 		onClientConnected: {
 			var urlPath = _request.url.toString();
 			if (urlPath.indexOf("/rpc/") === 0)