Diagonal Split with the Trim Tool

I’m trying to do guitar strumming just to see if it works and it can work but … it takes too much time !!!

There was this guy who used something other than Cubase in a Youtube video ages ago. I don’t remember but I’m almost certain it was Fruity Loops?
Even in that program you could diagonally split a number of notes and have both what’s before the split and after the split left on the screen.
This is more a split tool than a trim tool in Cubase-speak, right?

I’d love to be able to do diagonal splits for doing experimental arpeggios, guitar strumming and other arpeggiated chords and melodies of all sorts.
Lot’s of fun for everybody if you can chop MIDI notes up without losing either the start or the end of the notes.

I have a bonus request for the above to work as smooth as possible and that is that the layout of the notes in the Key Editor is adjusted a little.
I’d like them to have all the notes, black and white, on the keyboard to the left and among the notes in the editor the same size.
As it is now if you do a diagonal Split over the notes B to C and E to F you get a bump in say a chromatic scale. Not good enough.