  What if you could summon a tech-support person to pop up in
seconds in a live video on your digital device? And what if that
person could draw on the screen or even take over the device to
solve a problem?  Well, starting Oct. 18, you can do just that
with the latest in Amazon's Kindle Fire tablet line, the Kindle
Fire HDX. This help system, called the Mayday button, is the
most unusual feature of what is otherwise a mainly evolutionary
new model of the company's color tablets.  A better help system
isn't exactly the prime reason to buy a new tablet. After all,
tablets are supposed to be simple and easy to figure out. But
Mayday is consistent with Amazon's long, well-earned reputation
for customer support.  X-Ray for Music shows lyrics synchronized
to the song playing on the Kindle Fire HDX. Amazon  I've been
testing the Fire HDX, and it's a good, basic color tablet. This
latest model, which starts at $229 for the 7-inch-screen version
I used, is a definite improvement on last year's Fire HD, which
started