why it looks like that !?
UE4 Linux is still a work in progress, it’s not necessarily going to work on every version.
because of this A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums. Update your mesa drivers to the newest version and your problem should be gone.
I tried to update mesa drivers to ver.10 but it always fail ,
i bought a new graphic card and it fixed the problem