While we wait for this functionality to be added to Studio, here are 3 short macros to help with segment selection.

;======================================================================

;Select up to 500 segments in a document. For more segments, simply change the number in the appropriate line.

;Press Alt+Down to activate

;=======================================================================

!DOWN::  
Send ^{Home}
Sleep 200
Send !+{Down 500}
Return

;======================================================================

;Select up to 500 segments in a document, then clear them all. For more segments, simply change the number in the appropriate line.

;Press Alt+2 to activate

;=======================================================================

!2::
Send ^{Home}
Sleep 200
Send !+{Down 500}
Sleep 200
Send !{Del}
Return

;======================================================================

;Select up to 500 segments in a document, then copy source to target. For more segments, simply change the number in the appropriate line.

;Press Alt+3 to activate

;=======================================================================

!3:: ;Select up to 500 segments at once, then copy source to target
Send ^{Home}
Send !+{Down 500}
Sleep 200
Send ^{Insert}
Return