When I was using Emacs in LXTerminal, I always had such a problem. The "Alt + some_key" combination could open up a LXTerminal menu. For example "Alt + F" would open up the "File" menu of LXTerminal, instead of being a "Meta +F" command in Emacs. In GNOME Terminal, I was able to disable "Alt" being a shortcut key to terminal menu, but I could not do the same thing to LXTerminal. Could anyone please help? Thanks.