bug#57476: 29.0.50; Mouse wheel event ignored on Lucid build

[Po Lu]

Stephen Berman <stephen.berman@gmx.net> writes:

> 0. emacs -Q
> 1. Display a buffer with enough lines to scroll, e.g.:
>    C-x d /path/to/emacs/sources RET
> 2. Scroll mouse wheel
> => The buffers fails to scroll.
> 3. Type `C-h k' and then scroll the mouse wheel
> => The echo area shows no input, only the prompt "Describe the following
>    key, mouse click, or menu item: "
>
> I see this only on the Lucid build.  Also on Lucis, if I hold down
> mouse-1 or mouse-3 and simultaneously scroll the wheel, then the buffer
> does scroll.  After releasing mouse-1 or mouse-3, scrolling the wheel
> scrolls the buffer once by one line (either up or down).  Further
> scrolling of the wheel fails to scroll the buffer.

To be clear here, you are talking about wheel-up and wheel-down events,
correct?

Input extension builds do not normally report mouse-1 or mouse-3; that
only happens if the input extension could not be set up for some reason.