handle Leaders, Welds, Tiles and RichAnnos

src/Mod/TechDraw/Gui/ViewProviderProjGroupItem.cpp

@@ -168,6 +168,7 @@ bool ViewProviderProjGroupItem::onDelete(const std::vector<std::string> &)
     // get child views
     auto viewSection = getObject()->getSectionRefs();
     auto viewDetail = getObject()->getDetailRefs();
+    auto viewLeader = getObject()->getLeaders();
 
    if (isAnchor)
    {
@@ -196,6 +197,14 @@ bool ViewProviderProjGroupItem::onDelete(const std::vector<std::string> &)
            QMessageBox::Ok);
        return false;
    }
+   else if (!viewLeader.empty()) {
+       bodyMessageStream << qApp->translate("Std_Delete",
+           "You cannot delete this view because it has a leader line that would become broken.");
+       QMessageBox::warning(Gui::getMainWindow(),
+           qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
+           QMessageBox::Ok);
+       return false;
+   }
    else {
         return true;
    }