When I use the DataSource property of a ListBox or ComboBox, there is
always a selected item.  When I bind the control, I don't want anything
selected.  I have tried using the .SetSelected() method, setting,
selectedIndex to -1 (twice in a row, blah blah), setting SelectedItem
to null, etc.

listBoxInventorParts.DataSource = _selectedInventorParts;
listBoxInventorParts.DisplayMember = "InventorPartNumber";
listBoxInventorParts.ValueMember = "pkInventorPartId";

// Doesn't work
listBoxInventorParts.SelectedIndex = -1;

// Doesn't work
listBoxInventorParts.SelectedItem = null;

// Doesn't work
listBoxInventorParts.SelectedValue = null;

// Doesn't work
listBoxInventorParts.ClearSelected();

// Doesn't work
for(int i = 0; i < listBoxInventorParts.Items.Count; i++)
{
   listBoxInventorParts.SetSelected(i, false);
}

Nice.