Selects a range of text in the editable portion of the System.Windows.Forms.ComboBox.
If you want to set the start position to the first character in the control's text, set the start parameter to zero. You can use this method to select a substring of text, such as when searching through the text of the control and replacing information.
ComboBox.SelectionStart returns the lower value of the current selection. For example, Select(10, -4) selects the text from character position 6 through character position 10. If you now get the ComboBox.SelectionStart value, it will be 6 rather than 10.