#121001# fix issue which loading the xls file contain drawing, form control,…

#121001# fix issue which loading the xls file contain drawing, form control, graphic ... will enable the undo action

Reported by: Yan Ji
Patch by: Lei De Bin 
Review by: Li Jian Yuan

sc/source/ui/docshell/docsh.cxx

@@ -1412,6 +1412,7 @@ sal_Bool __EXPORT ScDocShell::ConvertFrom( SfxMedium& rMedium )
     }
     FinishedLoading( SFX_LOADED_MAINDOCUMENT | SFX_LOADED_IMAGES );
 
+    GetUndoManager()->Clear();
     // #73762# invalidate eventually temporary table areas
     if ( bRet )
         aDocument.InvalidateTableArea();