pagelayout_editor: lock panel update during widgets rebuild.

The rebuild is much faster.
From master branch

pagelayout_editor/dialogs/properties_frame.cpp

@@ -40,7 +40,7 @@
 #include "tools/pl_selection_tool.h"
 
 #include <dialogs/html_message_box.h>
-
+#include <wx/wupdlock.h>
 
 /**
  * Minimum drawing sheet text default size in millmeters from #PROPERTIES_FRAME.
@@ -236,6 +236,9 @@ void PROPERTIES_FRAME::CopyPrmsFromItemToPanel( DS_DATA_ITEM* aItem )
         return;
     }
 
+    // No not update display during rebuild:
+    wxWindowUpdateLocker noUpdates( this );
+
     wxString msg;
 
     // Set parameters common to all DS_DATA_ITEM types