public ToolStripTextBox () : base (new ToolStripTextBoxControl ())
{
ToolStripTextBoxControl text_box = TextBox as ToolStripTextBoxControl;
text_box.OwnerItem = this;
text_box.border_style = BorderStyle.None;
text_box.TopMargin = 3; // need to explicitly set the margin
text_box.Border = BorderStyle.Fixed3D; // ToolStripTextBoxControl impl, not TextBox
this.border_style = BorderStyle.Fixed3D;
}