A question for owners of the new Sonar

I don't think so.
 
Sonar will split it exactly on the Now time

OK, thanks...that confirms my [s u s p i c i o n s].  Splitting MIDI clips across notes causes some very strange behaviour in X3.  That the software doesn't offer you the 3x requisite choices indicates to me that it (still) doesn't handle this scenario correctly.
 
What the software should do is to detect clip splitting across MIDI notes and offer the three following choices to the user:
 
1. Split (cut) the notes across the two clips
2. Truncate the notes such that they lie within the left hand clip
3. Preserve the note length(s), requiring an extension of the left hand clip (i.e. producing overlapping clips)
 
What X3 does (and I assume the new version also) is to leave the notes 'hanging' outside of the limits of the clip which contains them.  Subsequent clip manipulation causes the software to behave in an undefined manner because of this.

Hmmm. I just tried it (again), and it is more or less displaying the behaviour in option 2. Again that's a default install of Platinum, with no settings migrated or altered. I say more or less because 'subsequent clip manipulation' shows the truncated notes will actually preserve their length if the clip is extended, as per option 3. I don't see that as being undefined, though it may not be what the OP wants it to do. The truncated notes are not hanging, in the sense that they have a proper note-off, even though they will extend back to their original length if you extend the clip. To me it offers reasonable flexibility, though an option to split the notes themselves, instead of non-destructively truncating them could be useful in certain circumstandes I suppose.
 
I looked for customization options but didn't find much (others may know of more) - in Preferences, with Advanced selected, down at the bottom under Customization -> Editing, there's a checkbox, apparently ticked by default, called Non-destructive MIDI editing. With this box unticked, the behaviour is different - then it will not split the clip exactly at the Now time, but rather at the end of any notes currently active at the Now time. I'm not sure why you would want that, but it's possible. That's the only thing I could find.

I've seen what ston is talking about.
 
Rears it's head if you split across a note the delete the right hand clip (i.e. no more MIDI to the right)
 
The cutoff note will simply continue to play for the duration of the song.
 
I've just learned to trim the note before I split.

bapu
I've seen what ston is talking about.
 
Rears it's head if you split across a note the delete the right hand clip (i.e. no more MIDI to the right)
 
The cutoff note will simply continue to play for the duration of the song.
 
I've just learned to trim the note before I split.

Hmmm. Have you tried it in Platinum? I have just tried it a number of times and each time the note that is truncated by the split stops playing correctly, no hanging involved. If you extend the clip to display the clipped note at its original length - or anything in between - it plays the correct, displayed length of the note, with a note-off. At least, here, so far, with the vsti's I've tried it on. Is anyone seeing otherwise in Platinum?
 

subtlearts

bapu
I've seen what ston is talking about.
 
Rears it's head if you split across a note the delete the right hand clip (i.e. no more MIDI to the right)
 
The cutoff note will simply continue to play for the duration of the song.
 
I've just learned to trim the note before I split.

Hmmm. Have you tried it in Platinum? 

No, but I will.

OK I played around with groove clip looping and step sequencer clips to see if I could identify any strange or unstable behaviour. Again, this is in Platinum, I might get around to firing up X3 again to see if it's any different.
 
So far, nothing. In fact, a step sequencer clip apparently can't be split at all, pressing S has no effect. Which is kind of odd, but there it is. A Groove clip behaves exactly the way a normal clip does - if I split it in the middle of a note, it non-destructively truncates that note, but if I subsequently manipulate the clip length it restores it to its original length or any part thereof, but so far it does so cleanly, with no hanging notes, meaning the clip end is producing a note-off wherever it truncates the note, and this seems stable and flexible.
 
Again, it seems to me that this is an acceptable state of affairs, at least as a default behaviour. So I would propose that your idea to have selectable behaviour is more of a feature request than a bug. It basically doesn't strike me as a big problem, but you might find others to support your position...