Axivion: Ensure buttons are exclusive

Avoid having none of the buttons selected which looks
confusing.

Change-Id: I445c4da970c4dfbd8a35228e31092c788d0b5d37
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/axivion/axivionoutputpane.cpp

@@ -736,6 +736,10 @@ public:
             if (auto issues = static_cast<IssuesWidget *>(m_outputWidget->widget(1)))
                 issues->updateUi();
         });
+        auto *butonGroup = new QButtonGroup(this);
+        butonGroup->addButton(m_showDashboard);
+        butonGroup->addButton(m_showIssues);
+        butonGroup->setExclusive(true);
 
         connect(m_outputWidget, &QStackedWidget::currentChanged, this, [this](int idx) {
             m_showDashboard->setChecked(idx == 0);