I wrote a AutoHotKey script to remap LWin to LAlt
LWin::LAlt
LWin & Tab::AltTab
LWin+Tab works OK. But I found, for example in my emacs, LWin+b can not work as Alt+b. And if I disable this statment
LWin & Tab::AltTab
LWin+b works. But I know LWin+Tab will not works very good without this remapping statement as mentioned in AutoHotKey Remapping.