If folder tracks containing MIDI tracks (when closed) and other MIDI tracks in addition are selected, if a note from a part (track) which is contained in a folder is selected and then modified, all parts from folders will immediately become unavailable and cannot be selected from the drop down list in the key editor. 
System specs? OS? Cubase version?
Hi,
Vista, Elements 6.0.7.
ATI graphics/AMD CPU, 2GB RAM
Similar behavior occurs if you select midi tracks of which one or more has a drum map attached.
I canāt recreate that here. The only thing that happens is when i have 2 or more parts selected and one or more has a drum map, it opens drum and key editors both.
Because the drum maps have different in and out notes, as well as different note names, current version of cubase doesnāt see them as the same and opens separate windows. Even opening 2 tracks with different drum maps opens 2 seperate editor windows.
Maybe something to shoot for in the future Steinberg? It would be great to select multiple tracks and just have them switch windows from the drop down list.
Hi Cin,
I believe it is due to XML being (or not being) used for one editor but not both.
As for the folder track issue, completely reproducible here, so long as any selected folder tracks are closed.
What I am hoping for is a complete revamp in the way folder tracks work and what facilities they may provide so anyone reading this, you may +1 when ready.
Explain the steps youāre going through to get this behavior.
I created 4 midi tracks with data on them.
Put 2 of them in a folder
Closed the folder
Highlighted the tracks in the folder and another track not in the folder.
Double clicked to open them in the Piano roll
edited some notes from a track in the folder
went to the drop down menu and selected another track not in the folder.
All tracks are viewable and available to edit in the current window.
Am I missing something?
Thank you for helping with this.
I think you will need to select the folder part rather than parts within the folder ātrackā itself if that makes sense.
Regards
I did this. Not working as you described. Iāve tried it several ways and I can always select and edit notes from any parts Iāve selected, regardless of which track theyāre on. 
Are you double clicking to open the piano roll or going to the MIDI menu?
What kind of editing are you doing to the notes? Iāve tried moving, stretching, deleting. All parts are still availableā¦
Iām going to the Edit menu and selecting and extending a note.
Not sure what you mean by that. How do you select OR extend a note in the Edit menu???
Aloha,
While in the āKey Edit Windowā I just select a note (MIDI Event) and drag it.
If āSnapā is āOnā the event will go to the next snap point.
If not drag/release it anywhere.
BTW
Can not reproduce prob here.
{ā-ā}