Actually my problem is xvkbd, not xbindkeys. If I just type
in the Debian chroot terminal, I get (after a bunch of warning messages) "a" on the next command line. Similarly when I use "\[parenleft]" I get "(". But with a lot of other special characters such as "\[percent]", I get nothing at all. Most but not all of the characters that I can compose with Fn are not produced, plus all that are on the virtual keyboard.

mscion, do you have the same phenomenon or is it just me?

The warnings that xvkbd issues look unrelated to my problem:

Code:

Warning: Cannot convert string "-*-lucidatypewriter-bold-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-bold-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-medium-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-medium-r-*-*-10-*-*-*-*-*-iso8859-1" to type FontStruct
xvkbd: Mode_switch not available as a modifier
xvkbd: although ISO_Level3_Shift is used instead, AltGr may not work correctly