Linux etc.

In /etc/X11/xorg.conf, in the keyboard section, I added the line:
Option “XkbOptions” “compose:ralt”
Now, I can type most accented characters and umlauts by first hitting the right ALT key.
A few examples (key combinations below all preceded by right ALT key):

` e: è (backtick followed by e)
” u: ü
, c: ç
s s: ß

Addendum
Changed this to […]

In ~/.Xmodmap

keycode 233 = F20
keycode 234 = F19

After changes, say:
xmodmap ~/.Xmodmap
This activates the keys that I have on the IBM X40 next to the up arrow key on the bottom right of the keyboard. Now, I can bind them to commands Xfce.
Then, I found a nice article on using the CapsLock key to type […]