Comment 1 for bug 1101982

I've uncovered the problem. There are two options in the XFCE control panel that do the same thing:

* Power Manager -> Extended -> Lock screen when going for suspend/hibernate
* Session and Startup -> Advanced -> Lock screen before sleep

The former seems to only control the behavior of the power manager panel applet (battery charge indicator). The latter seems to only control the behavior of the logout dialog and the action buttons panel applet. These settings ought to be merged because it is unlikely that a user would wish to have different behaviors depending on which applet they use to sleep the computer. Furthermore, enabling an inconsistent security policy is unsafe.