Hello guys as we where waiting for our flight to Geneva we made a few pictures ...
when I saw a Brussels Airlines 737 I wanted to photograph it ... but I for got to look at the reg ... so my friends told me it was OO-VEK but it's a -400 reg. the picture was taken at 06.00
Did forget to mention: flight SN2823 to BUD was also boarding around that moment, it was OO-VEX which has winglets. I guess this is the one you are searching for (letters X and K look the same). Other wingletted -300s are OO-VEG & OO-VEH, but both departed much later that day. The other two LTM & VEN have still no winglets.
Quite probably, since the plane is standing at the B pier. Only non-schengen countries are boarded at the B pier, and as BUD isn't in Schengen yet (Greece and Italiy are), it has to be that plane.