DataGridView Select Column AND Row Headers

[samoan2]

When selecting all rows and columns in a datagridview, is it possible to include both the column headers and row headers? I have the following code:

dgSummaryTable.SelectionMode = DataGridViewSelectionMode.ColumnHeaderSelect

I cannot seem to find an appropriate SelectionMode that allows me to select both the column headers and the row headers simultaneously. I can only select either the column headers or the row headers. Not both. If i need to use something other than DataGridView, advice would be much appreciated!