The Watch menu

Watch...-> Variable (Ctrl-J)

Opens a dialog where you can enter a variable that you wish to put on the watch list. For example “$test”.

Watch...-> Expression (Ctrl-V)

Opens a dialog where you can enter an expression that you wish to put on the watch list. For example “myFunc($test)”.

Watch...-> $this (Ctrl-T)

Puts $this on the watch list.

The rest of the items in the Watch... menu are convenience menues to put the contents of $_SERVER, $_ENV, $_SESSION, $GLOBALS, $_REQUEST, $_GET, $_POST and $_FILES on the watch list.