As usual while waiting for the next release - don't forget to check the nightly builds in the forum.
Very often, but not always, #defines in header files do not result in ungraying corresponding conditional blocks in the editor.The same for -D command line options for avr-gcc. Interestingly the command line symbol F_CPU is known to the editor.
Just keep in mind that the macro parser in Scintilla is primitive and doesn't support complex cases, so in theory this feature would never work reliably.