Except Josep is talking about a static text control, not a single line edit.
As far as I know, you cannot select the text of a static text control. The SelectText powerscript function doesn't exist for static text controls so I don't even think you could 'roll your own' easily. Sorry ... I know that doesn't help much
If you want to display uneditable text that can be selected, you could use a datawindow with a single column for the text to display and set that as display only. Maybe not ideal but could work