D instead of S on solo button on Midi Track

i don’t know if this is a cubase 6 issue - but i never experienced it before.
i cannot recreate what i did exactly - but suddenly there was an orange D button where the red solo button usually is (this is a midi track).
i cannot change it - whatever i try - the D just doesn’t go away and i cannot solo the midi track anymore, i can only do this by soloing the corresponding audio channel in the mixer.
i couldn’t find any reference to the D button in the supplied manual… what does it stand for - what does it do, and - how do i get rid of it?
it’s not a critical problem - but it makes me wonder that after over ten years of cubase this is the first time i came across it :wink:

Congratulations on finding Solo Defeat. [Alt]/[Option]-click. P. 154 in the C6 manual.

Wow, over 10 Years…, no reference in the manual…, congratulations from me too
btw. you can enable “show tooltips” in the preferences, which would have given you a hint by simply moving the mouse over the solo button…

… and there it is… P. 154…
Thanks Steve… in Chicago…
what a good way to learn about functions you never needed…
but just because of it… i’ll use it now… it wasn’t invane :wink: