close-button fix for macosx

src/gui/qt/createnetworkgamedialog/createnetworkgamedialogimpl.cpp

@@ -25,8 +25,9 @@
 createNetworkGameDialogImpl::createNetworkGameDialogImpl(QWidget *parent, ConfigFile *c)
       : QDialog(parent), myConfig(c)
 {
-
-    setupUi(this);
+	setWindowModality(Qt::ApplicationModal);
+	setWindowFlags(Qt::WindowSystemMenuHint | Qt::CustomizeWindowHint | Qt::Dialog);
+    	setupUi(this);
 	
 	myChangeCompleteBlindsDialog = new changeCompleteBlindsDialogImpl;