I would request this feature.  Either :
a. automatically prioritize first last
b. automatically prioritize first last but not absolutely, just increase speed of preview ... for instance first last downloaded in first 10% of file
(perhaps this option saves community pressure???)
c. on add torrent ... select for prioritize first last all files in torrent visible on form (of that can be made visible on form)


Otherwise the work around is :

1. ctril A select all
2. right arrow expand
3. repeat 1/2 several times until all files are visible - as they may scroll far away up or down you have to scroll up and down until you see they are all visble
4. ctrla A ... right mouse, scroll, right mouse, scroll etc... etc...  finally select prioritize first last ...
This is maybe 20 mouse operation of various sorts ... two finger operations, right click, left click, scrolling ...
- this is really not very user friendly at all.

Also say you do the above on a set of files, then add a few more ... you have to expand all the torrents in your window which can be a lot ... so the entire lot maybe hundreds of files are being expanded and so on.  Very inefficient

thanks to you