Index: trunk/Mars/mhbase/MFillH.cc
===================================================================
--- trunk/Mars/mhbase/MFillH.cc	(revision 17124)
+++ trunk/Mars/mhbase/MFillH.cc	(revision 17125)
@@ -581,4 +581,8 @@
 Int_t MFillH::PostProcess()
 {
+    // Return if fH was never initialized.
+    if (!fH)
+        return kTRUE;
+
     //
     // Now all data is in the histogram. Maybe some final action is
@@ -602,10 +606,11 @@
     {
         const TString opt(MString::Format("nonew %s", fDrawOption.Data()));
-        fCanvas->cd();
+        // fCanvas->cd();
+        // fCanvas->Clear();
+
         // Remove the old class to prevent clashes calling
         // Paint-functions when the display is updated
         fCanvas->GetListOfPrimitives()->Remove(fH);
-        // DrawClone also takes care of calling gPad->Clear()
-        fH->DrawClone(opt);
+        fCanvas->GetListOfPrimitives()->Add(fH->Clone(), opt);
         fCanvas->Modified();
         fCanvas->Update();