Maybe the 3DS emulates the DS and therefore can only run that DS application at that time, and as it requires quite a bit of RAM it cannot run another app simultaneously. Another reason could be also that when running a DS game on the 3DS the upper screen is a slightly 'off' and pixelated even when readjusted with the start and select before boot up of the DS game.
Source: http://www.youtube.com/watch?v=I9zMIs5-SZI...&lf=mh_lolz
Please watch in HD if able to, really makes a difference.
Source: http://www.youtube.com/watch?v=I9zMIs5-SZI...&lf=mh_lolz
Please watch in HD if able to, really makes a difference.