how to set focus to a textbox when clicking a cell in a datagrid?

Right -- so the problem is that the CurrentCellChanged fires telling you that we're changing to the new cell. You then set your TextBox to be focused, and it is -- really briefly. The textbox in the grid then rips focus away.

I don't know of a nice way around this, so I'll give you a slightly non-nice way: when the currentchanged fires you say "I'd really like focus to go to my textbox" by setting a flag. When the grid's TextBox gets focus, you rip focus away to your textbox (it's only fair).

Dim dt As DataTable
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
dt = New DataTable("foo")
dt.Columns.Add("id")
dt.Columns.Add("f")
dt.Rows.Add(New Object() {"a", True})

dt.AcceptChanges()

Dim ts As New DataGridTableStyle()
ts.MappingName = dt.TableName
DataGrid1.TableStyles.Add(ts)

Dim tc As New DataGridTextBoxColumn()
Dim dc As DataColumn
For Each dc In dt.Columns
tc = New DataGridTextBoxColumn()
tc.MappingName = dc.ColumnName
AddHandler tc.TextBox.Enter, AddressOf FocusedTextBoxColumn
ts.GridColumnStyles.Add(tc)
Next
DataGrid1.DataSource = dt

End Sub

Dim focusTextBox As Boolean = False
Private Sub DataGrid1_CurrentCellChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DataGrid1.CurrentCellChanged
focusTextBox = True
End Sub

Sub FocusedTextBoxColumn(ByVal o As Object, ByVal e As EventArgs)
If focusTextBox Then
textBox1.Focus()
focusTextBox = False
End If
End Sub