I’m neutral on the piano-roll issue, its just interesting to see different methods.
I usually notate —> that way, on the go, on my PSP text editor.
More stuff…
Klavar notation via wiki “notation”.
Rondo “…horizontal live playing keyboard and visual track filtering…” The “piano” can be also moved up or down.
Reason I would prefer per-track piano roll is that I could both separate chord work from percussion/plain noise AND still see big picture of note relations WHILE still having everything in vertical context in single timeline. Separated automation is already pain in the ass to edit, forcing constant checks of numbers to see if changes happen at correct notes. I wouldn’t wish similar timing problems with piano roll. What I would like to see is track option to view it as either piano roll or tracker and having option to view and edit automation curves overlaid on note data or placed just right of them.
And single track vertical piano roll could show notes from other tracks ghosted/dimmed with their their track color (it could jump tracks with click on such note).
Whoah!!! I like Horizontal live playing keyboard a lot!!! This could solve all problems?
Imagine those horizontal tracks to be double-clickable and each track will open its own pattern editor [with that instrument only OR a classical pattern [with its name on the top].
Anyway - image talks more than words:
these vertical piano rolls are heresy and you will all be burned at the stake for this witchcraft… 
I think this is quite arguable:
Why would you care for a horizontal flow similar to traditional sheet music when you’re used to a tracker in which you edit, read and play music in a vertical fashion ?
A tracker is somehow an evolution of a barrel organ or an automatic piano (pianola?) where notes are played vertically, be it with perforated paper or real piano rolls.
As for your arguments regarding sheet music, I think this is as legitimate a reason to display it vertically.
A vertical piano roll view in Renoise could be displayed next to its track view to make it easier to spot problems.
A vertical piano roll means a horizontal keyboard display, similar to the view you have when you play a real keyboard (well, traditionally at least 
)
So, while I’m used to horizontal piano rolls in other DAWs I think it would be counterproductive in Renoise as it would force users to continually switch between horizontal and vertical thinking.
That said, I’m not sure I’m actually missing a piano roll 
Den
welcome to the forum!
now on with the debate…
okay… i’ve thought about this, its actually a little more complicated than i first thought to explain why. but its definitely more of a functional thing than a notion of tradition for the sake of it:
firstly, although i’m used to the vertical flow of time in a tracker, pitch is only expressed by numbers and characters (c4 etc.) so in fact the concept of pitch is not currently expressed in a vertical or horizontal fashion, in the main tracker window. only time is. i have nothing against a vertical flow of time (obviously, or i wouldn’t be using a tracker), it is the idea of pitch being expressed on a horizontal left-right axis where left is lower pitch and right is higher pitch that bothers me.
the reason for this is that it seems more logical to me to express a lower pitch on a vertical axis where the bottom is a low note and the top is a higher note, than it does for left to be a lower note and right to be a higher note. now this may indeed be only due to previous exposure to stuff like sheet music, guitar tab, other piano rolls. but nonetheless down is low and up is high in my mind, and lower notes are a lower frequency (not a more leftward frequency), and higher notes are a higher frequency (not a more rightward frequency). you move up and down the neck of a guitar, or up and down the piano (even though its left-right in orientation). it just seems more logical for pitch to be described on an up-down axis to me.
i would also point out that there is already horizontally scrolling stuff in renoise: the automation, the instrument editor envelopes, the sample editor. i think all these things would be much more confusing if they were turned at 90 degrees for the same reason: filter cutoff values make more sense expressed as down the axis=lower value, up the axis=higher value. usually, unless circumstances of design prevent it, you want to move sliders vertically up and down to control volume on a mixer. a left-right axis is usually reserved for situations where it makes sense - you twist a dial left or right to control panning for example. or a dj moves a crossfader left or right because one turntable is on his/her left, the other on the right. up and down is better for high-low scenarios, not left-right. i think its for this reasons that a piano roll should be horizontal scrolling, where pitch is expressed on a vertical axis, because pitch is fundamentally low-high more than it is left-right.
well i guess this is a good arguement. however a piano roll is in some ways more useful for pitching notes visually than it is for timing them. i don’t see having an indication of bars/ticks etc. horizontally with the piano roll as particularly restrictive. timing of notes can still be assessed vertically in the normal way. if there is an option to view multiple tracks in the piano roll it makes no odds if its horizontal or vertical anyway to spot problems.
yes, i know, this makes it much harder to argue my case 
. however i still think the piano roll should be vertical for the reasons i’ve already described.
i think not, because like i already said, automation, instrument and sample editor already use time horizontally. its not that big a deal to have time horizontal for the piano roll too. i think its preferable to forcing people to think of pitch horizontally rather than vertically.
and thats the other key thing i think - piano roll is mainly going to have an appeal for people inputing more complex melodic note information, perhaps with chords and so forth. if you’re not doing more complicated stuff with lots of different simultaneously pitched notes, complex chords and stuff, or your already so familiar with tracking that you can do this stuff anyway you really don’t need a piano roll… but otherwise you might find it useful. my guess would be that a real pianist would be more likely to have use for a piano roll than someone who programmes beats and melodically simple basslines. and in that situation the pianist is more likely to be used to reading sheet music or similar which goes left to right in time and up-down in pitch. even if that is only because its the way it is in 99% of music notation… i still think thats a good enough reason.
after all that analysis, i think i could probably get used to a vertical scrolling piano-roll… i’m just not sure i should have to, or that even if i did there would be any real benefits.
Well, I must admit that I would feel very uncomfortable if waveforms and envelopes were displayed vertically. If Renoise was to offer audio tracks -I’ve seen mockups in the forum- it would be just plain awful if they were displayed vertically.
Also, I just spent an hour toying with Renoise and Reaper rewired, and I kept switching between the two programs: instant accommodation.
(If that couple proves stable with Rewire, it’s probably as good an option as having audio tracks in Renoise, if not better IMO)
Furthermore, while I don’t know what amount of ‘editability’ (for lack of a better word) would be put into a piano roll in Renoise, I guess it would help attract new users, especially if it was displayed horizontally.
Maybe a split view could be useful. Upper and lower frames hidden, track view in the upper half of the screen, piano roll in the lower half, selected item(s) highlighted in both views, a vertical bar in the piano roll and an horizontal bar in the tracker view to emphasize the current ‘playhead’ position…
So yes, after reading your reply and a few second thoughts, I think horizontal is probably the way to go 
i don’t see what the problem is then tbh. it works great for keyboard players (and i think most of them would like the horizontal pianor roll a lot more than the vertical if they’ve never worked with any music software previously)
Yes!
A pianoroll like in Rondo will make editing easier.
Also the turn of the direction (flying hex/blocks from top to down) will the absolut bomb! I have suggested this weeks ago.
I see no trouble if it can be handled like the pattern-arranger. Nobody must use it and can hide it!
So i think if it is clever integrated you can decide by time and can feel happy that you are one mousclick away from it.
How many are troubeling about the arranger and now use it?
Think about …