[AUCTeX] Preview: Toggling all previews' visibility on/off at once?

[gojjoe]

Dear All,

Could someone here help me creating a particular function in 
AUCTeX-preview? Also, I wonder if such a function would be 
of interest to other people too, to submit it as a feature 
request:

In Preview, it would be useful to have a function that 
toggles on/off the visibility of all previews in the buffer, 
independently of the position of point. The key word here is 
*toggle*, rather than *regenerate*.

The function preview-at-point only toggles one preview, and 
only if the point is positioned on the preview. So if one 
only needs to take a quick look at the LaTeX code of a 
couple of formulae above or below point, one must:
1. move point to the preview,
2. call preview-at-point (or mouse-2),
3. take a look and memorize the code of interest,
4. call preview-at-point,
5. move point back.

The other option is to clear all previews (say in the 
section) and then regenerate them – but this can take time 
in buffers with many formulae, and is simply a waste of 
resources.

I tried to use/reverse engineer the functions 
"preview-at-point" and "preview-toggle" to build a function 
that toggles all previews at once, but failed (I don't 
understand how the "overlay" argument works in those 
functions). If anyone can suggest a method to do this, I'd 
be very grateful!

Cheers,
J