The version of lxappearance in the repository doesn't seem to work.
The description still says it is compiled for TC 3.0 instead of 4.0.
When it runs, it segfaults with the following error message (in dmesg output):
lxappearance[13407]: segfault at c ip b74973d9 sp bf823620 error 4 in libgtk-x11-2.0.so.0.2400.8[b738b000+3c4000]
All of the other LXDE components (that I have tested) seem to work fine.
This extension probably just needs to be recompiled for TC 4.0