RE: Fix some tooltip related problems

[Drew Adams]

(If this has no effect on users or Lisp then you can
ignore this message.)

Could you perhaps describe the changes in terms of what
changes for (1) users and (2) existing Lisp code?  And
could you describe the problem(s) it is meant to solve?

> Replace 'tooltip' frame parameter with a 'tooltip'
> member in the frame structure.

I don't find a `tooltip' parameter mentioned in the
docs (e.g. Emacs 26 pretests).  Is this related to
variable `tooltip-frame-parameters'?

If so, this might break code (of which I have some)
that uses that variable to configure tooltip frames.

Does this affect use of `x-show-tip' or `tooltip-show'?

> For modeline help-echoing have tooltips show applicable
> actions only.

What does that mean?  What "inapplicable" stuff will
users no longer be able to see in tooltips?