Hi! 
First of all: Thanks for a wonderful software! I just kicked KDE over the edge
and use XFCE wherever I go (laptop, desktop, server, office pc).

Now, on my Acer Laptop I have a number of "special" keys for which I load a
special kernel module (acer-hk). This module allows using these keys by adding
keycodes for them.

I run xmodmap in my /etc/xdg/xfce4/xinitrc to bind those four keys to
F17,F18,F19 and F20. When I logged into my XFCE and start xev, I can see that it
regconizes the keys correctly (as F17-F20, when I press them). 

Now I used the shortcut editor (Setup -> Windows Manager -> Keyboard) and setup
a shortcut to start my favourite webbrowser when I press on the "Web" key (AKA
F20). The Shortcut editor correctly says "firefox" --> "F20" afterwards and I
can press the button and Firefox comes up. 

But: When I log out and log in again, this does not work anymore. No Firefox
after pressing F20. I again checked that F20 is shown in xev and then start my
shortcut editor just to find out that firefox is still assigned to F20 ... but
it doesn't work anymore. Strange as it is, if I reconfigure the shortcut (double
click on the assigned key) to F20 again, it works afterwards. Unfortunately only
for that session, after a fresh login it's the same thing again. No Firefox..

Reproducible: Always
Steps to Reproduce:
1. Assigned special keys to F17 - F20 in xinitrc by using xmodmap
2. setup F20 to start firefox in shortcut editor
3. test it, works fine (firefox comes up after pressing F20)
4. logout and re-login
5. press F20, nothing happens
Actual Results:  
the special keys are not regconized properly after a fresh login. I need to let
shortcut editor learn the keys in a session in order to use them in that session.

Expected Results:  
After a fresh login, those keys should work without any further configuration
besides the one-time setup procedure in shortcut editor

I am using Gentoo and XFCE 4.2.2 ...