[Gui] Disable the ability to change themes and preference packs...

src/Mod/Start/Gui/StartView.cpp

@@ -49,6 +49,8 @@
 #include <Base/Tools.h>
 #include <Gui/Application.h>
 #include <Gui/Command.h>
+#include <Gui/View3DInventor.h>
+#include <Gui/View3DInventorViewer.h>
 #include <gsl/pointers>
 
 using namespace StartGui;
@@ -476,6 +478,17 @@ void StartView::firstStartWidgetDismissed()
 
 void StartView::changeEvent(QEvent* event)
 {
+    _openFirstStart->setEnabled(true);
+    Gui::Document* doc = Gui::Application::Instance->activeDocument();
+    if (doc) {
+        Gui::View3DInventor* view = static_cast<Gui::View3DInventor*>(doc->getActiveView());
+        if (view) {
+            Gui::View3DInventorViewer* viewer = view->getViewer();
+            if (viewer->isEditing()) {
+                _openFirstStart->setEnabled(false);
+            }
+        }
+    }
     if (event->type() == QEvent::LanguageChange) {
         this->retranslateUi();
     }