Change to NativeComboBoxStyle for DataGrid

I've been trying create a style based on the EditorsCommonDictionary.NativeComboBoxStyleKey style for use in a data grid (by setting DataGridComboBoxColumn.EditingElementStyle).

This should be a simple style, with setters for Padding, BorderThickness & FocusVisualStyle, but unfortunately, the control template doesn't respect the BorderThickness setter, so I have had to duplicate the entire control template in my style.

Would it be possible to add a BorderThickness="{TemplateBinding BorderThickness}" attribute to the ToggleButton element? Note I have only checked this for the NativeComboBoxStyleOfficeGenericKey style, and only for the standard template, not when IsEditable=True, but I imagine similar changes would be needed for the other themes.

Phil