I've modified the default X keymap so that the "Alt" key sets the X Mod1
(AKA Alt) modifier, and the "Windows Logo" set the X Mod4 (AKA Meta)
modifier. This deviates from the default which overloads the "Alt" key
to set both modifiers, a holdover from the day when keyboards didn't
have the additional mod key needed to emulate a terminal.
For a long time (and a just re-tested) rxvt and multi-gnome-terminal
respected the difference between the "Alt" key and the X Mod4 modifier.
As an example: At the bash prompt (thanks to readline and the emacs key
bindings), I type some words, then press Meta-b (hold the "Windows Logo"
key while pressing the "b" key) to move the cursor back a word at time.
gnome-terminal however ignores the "Windows Logo" key, and instead
requires I hold the "Alt" key.
Please change gnome-terminal to recognize both Mod1 and Mod4 as Meta by
default for backwards compatibility. Please also allow a "respect the
windowing system key binding" setting so I can use my Mod4 (Meta) key
for readline Meta, while at the same time I can use my Mod1 (Alt) key to
access the window's menu bar via keyboard shortcut (Alt-b for Tabs
menu).