Login dialog can't be closed now during a sign in request.

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/branches/uni@13308 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/states_screens/dialogs/login_dialog.cpp

@@ -163,7 +163,7 @@ void LoginDialog::onEnterPressedInternal()
 
 bool LoginDialog::onEscapePressed()
 {
-    return false;
+    return m_cancel_widget->isActivated();
 }
 
 void LoginDialog::onUpdate(float dt)