RE: finding the face of a popup

[Drew Adams]

> > I believe that the description of a face given by placing point
> > over a field and typing C-u C-x = should tell you
> > the face of a popup that is triggered when the mouse is over that
> > field.
>
> I think the problem with that is that you are mixing up two different
> levels of the application. The popup/tooltip is a function of the mouse
> location. The  C-u C-x = describes what is around point and the
> tool tip is not really around point

1. See library facemenu+.el, which enhances standard library facemenu.el in
various ways.

In particular, it uses the mouse pointer position when Text Properties >
Describe Properties is accessed from the mouse popup menu ('C-mouse-2').

So, instead of using `C-x =', you can just point the mouse where you want,
use `C-mouse-2' to bring up the Text Properties menu, and choose menu item
Describe Properties. You'll see a description of the text properties at the
mouse pointer position (not the text cursor position).

http://www.emacswiki.org/cgi-bin/wiki/FaceMenuPlus#TextPropertiesMenu


2. However, this won't help with the problem raised by the OP, because Emacs
never lets the mouse pointer point to a tooltip: as soon as you move the
mouse toward the tooltip, the tooltip disappears. That's TRT.

I really think that there is no great solution to this, which I also don't
think is a big problem. If you know that a tooltip is called a "tooltip"
(and many users do nowadays), then you can use `apropos', as suggested. If
you don't know that, then you can use `list-faces-display', as suggested,
and check each face that looks like what is used for tooltips - there are
probably not 36 such faces.