[LINUX] Thingies found while running Garry's Mod's Linux version

Well, looks like Linux Garry’s Mod version isn’t “Stable”.

So here are my problems:

I recently installed GNU/Linux on my computer, along with the Ubuntu distro. Downloaded Steam, timepassesfast, Initialized the game and It run perfectly well EXCEPT FOR:

. Discommunnal Lag on using ANY Post-Processing (Not happens in Windows)
. Insert Menu (‘Q’ menu) works but I can’t change categories, and on inserting objects it only selects them, with that damn pink overlay (Not happens in Windows)
. Upon pressing F1, F2, F3, F4, instead of opening the HELP/Insert menu, Menu1, Menu2, Menu3 respectively, it opens a series of debugging tools, thus making Impossible of inserting objects

Help appreciated?