Function: scan-buf-next-region

Go to the start of the next region with non-nil help-echo.
Print the help found there using `display-local-help'. Adjacent
areas with different non-nil help-echo properties are considered
different regions.

With numeric argument ARG, move to the start of the ARGth next
help-echo region. If ARG is negative, move backward. If point
is already in a help-echo region, then that region does not count
toward ARG. If ARG is 0 and point is inside a help-echo region,
move to the start of that region. If ARG is 0 and point is not
in such a region, just print a message to that effect. If there
are not enough regions to move over, an error results and the
number of available regions is mentioned in the error message.

A potentially confusing subtlety is that point can be in a
help-echo region without any local help being available. This is
because `help-echo' can be a function evaluating to nil. This rarely happens in practice. (fn &optional ARG)