Avoid Qt warning re mdi window not in workspace

src/Mod/TechDraw/Gui/ViewProviderPage.cpp

@@ -28,6 +28,7 @@
 # include <QAction>
 # include <QMenu>
 # include <QTimer>
+#include <QList>
 #include <QPointer>
 #include <boost/signals2.hpp>
 #include <boost/signals2/connection.hpp>
@@ -71,7 +72,8 @@ PROPERTY_SOURCE(TechDrawGui::ViewProviderPage, Gui::ViewProviderDocumentObject)
 
 ViewProviderPage::ViewProviderPage()
   : m_mdiView(0),
-    m_docReady(true)
+    m_docReady(true),
+    m_pageName("")
 {
     sPixmap = "TechDraw_Tree_Page";
 
@@ -91,6 +93,7 @@ void ViewProviderPage::attach(App::DocumentObject *pcFeat)
     auto feature = getDrawPage();
     if (feature != nullptr) {
         connectGuiRepaint = feature->signalGuiPaint.connect(bnd);
+        m_pageName = feature->getNameInDocument();
     } else {
         Base::Console().Log("VPP::attach has no Feature!\n");
     }
@@ -117,12 +120,21 @@ void ViewProviderPage::show(void)
 
 //this "hide" is only used for Visibility property toggle
 //not when Page tab is closed.
+//WF: is this right? same behaviour either way.
 void ViewProviderPage::hide(void)
 {
     if (!m_mdiView.isNull()) {                                //m_mdiView is a QPointer
         // https://forum.freecadweb.org/viewtopic.php?f=3&t=22797&p=182614#p182614
         //Gui::getMainWindow()->activatePreviousWindow();
-        Gui::getMainWindow()->removeWindow(m_mdiView);
+        QList<QWidget*> wList= Gui::getMainWindow()->windows();
+        bool found = wList.contains(m_mdiView);
+        if (found) {
+            Gui::getMainWindow()->removeWindow(m_mdiView);
+            Gui::MDIView* aw = Gui::getMainWindow()->activeWindow();  //WF: this bit should be in the remove window logic, not here.
+            if (aw != nullptr) {
+                aw->showMaximized();
+            }
+        }
     }
     ViewProviderDocumentObject::hide();
 }
@@ -203,11 +215,16 @@ bool ViewProviderPage::showMDIViewPage()
             (pcObject->getDocument());
         m_mdiView = new MDIViewPage(this, doc, Gui::getMainWindow());
         QString tabTitle = QString::fromUtf8(getDrawPage()->getNameInDocument());
+
+        m_mdiView->setDocumentObject(getDrawPage()->getNameInDocument());
+        m_mdiView->setDocumentName(pcObject->getDocument()->getName());
+
         m_mdiView->setWindowTitle(tabTitle + QString::fromLatin1("[*]"));
         m_mdiView->setWindowIcon(Gui::BitmapFactory().pixmap("TechDraw_Tree_Page"));
         m_mdiView->updateDrawing();
         Gui::getMainWindow()->addWindow(m_mdiView);
-        m_mdiView->viewAll();
+        m_mdiView->viewAll();  //this is empty function
+        m_mdiView->showMaximized();
     } else {
         m_mdiView->updateDrawing();
         m_mdiView->redrawAllViews();

src/Mod/TechDraw/Gui/ViewProviderPage.h

@@ -87,6 +87,7 @@ protected:
 private:
     QPointer<MDIViewPage> m_mdiView;
     bool m_docReady;
+    std::string m_pageName;
 };
 
 } // namespace TechDrawGui