Compile of xfce-settings-4.7.3 fails with:

gmake[2]: Entering directory `/var/tmp/xfce47/xfce4-settings-4.7.3/xfce4-settings-helper'
  CC     xfce4_settings_helper-keyboards.o
keyboards.c: In function `xfce_keyboards_helper_restore_numlock_state':
keyboards.c:236: error: `XK_Num_Lock' undeclared (first use in this function)
keyboards.c:236: error: (Each undeclared identifier is reported only once
keyboards.c:236: error: for each function it appears in.)
gmake[2]: *** [xfce4_settings_helper-keyboards.o] Error 1
gmake[2]: Leaving directory `/var/tmp/xfce47/xfce4-settings-4.7.3/xfce4-settings-helper'
gmake[1]: *** [all-recursive] Error 1

Which seems to imply that whichever header file declares XK_Num_Lock isn't being #include'd

On Solaris, this would be

#include <X11/keysym.h>

and adding that to keyboards.c fixes the problem for me, but I have no idea whether that fix is generally correct.

(This seems to be a side-effect of the fix for #3098.)