[Kitten]

pawn Код:

new string[128];
strcat(string,"Line 1\nLine2\nLine3\nLine4\nLine5\nLine6\nLine7\nand so on");
ShowPlayerDialog(playerid,dialogid,DIALOG_STYLE_MSGBOX,"Commands",string,"Close","");

EDIT:

Dubya why are you using the callback OnDialogResponse when it's just showing a message it's not responding to anything.