When I run your sample, I do not see a problem unless I change my regional setting so that the string 02/10/2005 will be interpreted as Oct 10. I assum ethis is the problem you are seeing too. If so, you can avoid it by handling the CurrentCellShowingDropDown event as below.
private void gridControl1_CurrentCellShowingDropDown(object sender, GridCurrentCellShowingDropDownEventArgs e)
{
GridCurrentCell cc = this.gridControl1.CurrentCell;
if(cc.Renderer is GridDropDownMonthCalendarCellRenderer)
{
GridDropDownMonthCalendarCellRenderer cr = cc.Renderer as GridDropDownMonthCalendarCellRenderer;
if(cc.Renderer.ControlValue != null && cc.Renderer.ControlValue != DBNull.Value)
{
DateTime dt = (DateTime) cc.Renderer.ControlValue;
cc.Renderer.ControlText = dt.ToString("g");
}
}
}