title: How to avoid System.DBNull in DataTable from DataGridView when saving changes?
body: <p>I have some DataGridViews each displaying one DataTable from a DataSet with multiple DataTables.</p>
  
  <p>When adding a new row to a DataGridView and saving it to the DataSet, bool columns have a System.DBNull-Value which causes an exception later (when reading the DataSet in an other application).</p>
  
  <p>Only if the checkboxes in my bool column are checked and then unchecked, it has a valid value of false when saving the DataSet.</p>
  
  <p>How can I ensure, that checkbox columns always have a default value of false when adding them to my DataGridView or saving them?</p>