"signalling" vs "signaling"

[gls@Think.COM (Guy Steele)]

I prefer two L's myself, but quite illogically so.  There is a rule of
thumb here: when forming participles, the final consonant of the verb root
is doubled if and only if it is a lone consonant *and* an accent falls on
that syllable.

Here is an ex post facto explanation for this I have just now constructed.
The main reason for doubling a consonant in this way is to make it clear
that the preceding vowel is not to be lengthened, because when you form a
participle it is unclear whether a final vowel-lengthening silent "e" was
dropped when the participial ending was attached.  However, if the final
syllable is unaccented then it is extremely unlikely to contain a long
vowel (it's hard to pronounce), and so consonant doubling would be
redundant and is therefore not done.

In this case, one can see that on paper (or CRT) "signaling" looks
as though it ought to be pronounced "signailing"; but just try to
say it out loud without shifting the accent to the second syllable.

English spelling stinks.

This is not to say that KMP's preference (mine also) should be overridden.
This is just background information.

--Guy