i do this glitch on khail.
Its a wonderful thing to use when checking for campers...
Like Czar mentioned.. This is an unsolved graphical bug in many games not just WR.
In almost any game (even the Nintendo 64 zelda game), wolfenstein, GTA, counterstrike, maplestory, where you can lean or switch camera angle slightly in corners, you can peek through walls.
I dont see how it would do you any good in maplestory?