I am running the demo mod that comes with Eclipse (I just started modding today) and when I run it, minecraft opens but only the backround of the home screen appears like this: http://i.imgur.com/x2kv2e0.png
I had an earlier error when it wouldnt run at all and I fixed that by changing the alternate jre to jre7 (jre8 was selected which had caused the problem).
This is the error code- [03:54:53] [sound Library Loader/INFO]: Sound engine started
[03:54:54] [MCO Availability Checker #1/ERROR]: Couldn't connect to Realms
[03:54:58] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:music.menu
[03:55:14] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:music.menu