michele@michele-K53SC:~/UnrealEngine$ sudo su
root@michele-K53SC:/home/michele/UnrealEngine# make SlateViewer
bash "/home/michele/UnrealEngine"/Engine/Build/BatchFiles/Linux/Build.sh SlateViewer Linux Development  
Building SlateViewer...
Using clang version '3.5.0' (string), 3 (major), 5 (minor), 0 (patch)
Creating makefile for SlateViewer (no existing makefile)
Performing full C++ include scan (no include cache file)
Building UnrealHeaderTool...
Using clang version '3.5.0' (string), 3 (major), 5 (minor), 0 (patch)
Target is up to date.
Parsing headers for SlateViewer
  Running UnrealHeaderTool SlateViewer "/home/michele/UnrealEngine/Engine/Intermediate/Build/Linux/x86_64-unknown-linux-gnu/SlateViewer/Development/UnrealHeaderTool.manifest" -LogCmds="loginit warning, logexit warning, logdatabase error"
Refusing to run with the root privileges.
Error: Failed to generate code for SlateViewer - error code: CrashOrAssert (3)
UnrealHeaderTool failed for target 'SlateViewer' (platform: Linux, module info: /home/michele/UnrealEngine/Engine/Intermediate/Build/Linux/x86_64-unknown-linux-gnu/SlateViewer/Development/UnrealHeaderTool.manifest).
make: *** [SlateViewer] Errore 3