XFCE4 start-up actions

I was recently at my folks' for the holidays and plopped-in Zenwalk 5.2 on an old system they have there. One thing I wanted Xfce4 to do when Mom logged-in was to

$xgamma -gamma 0.7

startup

To solve this, I created a .desktop file (I named mine xgamma.desktop) made it executable (chmod 755 xgamma.desktop), and placed it in the xfce autostart folder (~/.config/autostart). This format for the .desktop file worked the first time:

[Desktop Entry]
Encoding=UTF-8
Version=1.0
Type=Application
Name=xgamma
Comment=takes screen to .7 bright
Exec=xgamma -gamma 0.7
StartupNotify=false
Terminal=false

I then logged-out. After logging back in, the screen went to 0.7 brightness automagically.