So, I'm the second developer on the project, nice to meet you.
SFGUI seems to break the SFML
Would be nice to know how, so it can be fixed. This is clearly a bug if it can be reproduced.
It seems that if we not use resetGLStates in Login constructor, we can't draw with SFGUI.
But, after, we can't draw with SFGUI and SFML at the same time in World class.
If you can take a look on Login.cpp, remove "Window->resetGLStates()" or try to draw a minimal GUI in World.
Maybe, that I don't know how to use completely SFGUI, I've thought we can use popGLStates/pushGLStates, but it's a loss of performance, right ?
[Sorry, for my bad English]