You should remove lxpanel from the system startup so only xfce4-panel will be starting.
If I remember well, check file:
~HOME/.config/lxsession/LXDE/autostartand put # before @lxpanel:
#@lxpanel --profile LXDE
OK. The problem is, I installed from a usb flash drive burned with unetbootin to the hard drive but the OS won't boot - it hangs up after finding the logitech usb mouse and just sits there. And PS2 mice are scarce these days.
Also, I haven't been able to get to it except on the week-end, and some weeks not even then. I am currently downloading the latest Sparky Xfce iso, to give that one a try.
I have had problems with the recent releases of ALL the Operating Systems I have installed with the exception of one, which happens to be the one that didn't make the change to systemd (openSUSE, Manjaro and Debian made the change) which may or may not be a coincidence.
Also, some of the other distros based on Debian Testing (i.e LMDE and SolydXK) changed to the stable edition.
My most stable system at present is CLDX (Calculate-Linux Desktop, Xfce), which is an Overlay of Gentoo (which Chrome OS is based on). Gentoo is a rolling distro that is stable but difficult to install (although Calculate isn't) and Sabayon has had it's own problems (including with it's forum). Calculate offers KDE and Xfce but not LXDE - your speciality.
You might want to consider branching out or experimenting with a LXDE version of either Gentoo or openSUSE (which is now upgradable via zypper dup and has a rolling version).
Slackware and it's derivatives are stable and systemd free but installing Wine can be a problem (which I need for two Windoze apps I depend on).
Calculate integrates it's desktop versions with it's servers.
Just a suggestion.