If no text is selected in the control, this property indicates the insertion point for new text. If you set this property to a location beyond the length of the text in the control, the selection start position is placed after the last character. When text is selected in the text box control, changing this property can release the value of the ToolStripComboBox.SelectionLength property. If the remaining text in the control after the position indicated by the ToolStripComboBox.SelectionStart property is less than the value of the ToolStripComboBox.SelectionLength property, the value of the ToolStripComboBox.SelectionLength property is automatically decreased. The value of the ToolStripComboBox.SelectionStart property never causes an increase in the ToolStripComboBox.SelectionLength property.