Exactly what is it that you want to do?
Do you want to change the value of the currentcell from a dialog in a button handler?
If so, here is a button handler that worked for me in a little sample.
Dim r As New Random
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim colIndexOfCol1 As Integer = Me.GridGroupingControl1.TableControl.Model.NameToColIndex("Col1") ''some columname
Dim currentRow As Integer = Me.GridGroupingControl1.TableControl.CurrentCell.RowIndex
Dim currentCol As Integer = Me.GridGroupingControl1.TableControl.CurrentCell.ColIndex
If (currentCol = colIndexOfCol1) Then
MessageBox.Show("test") ''some dialog
Me.GridGroupingControl1.TableControl.Table.CurrentRecord.SetValue("Col1", r.Next(10000))
End If
End Sub