bug#13523: 24.2.92; [regression] mark-active

[Glenn Morris <rgm@gnu.org>]

So IIUC the issue can be summarized as:

down-mouse-1 runs mouse-drag-region
mouse-1 runs mouse-set-point

mouse-drag-region calls mouse-drag-track.
Since 2010-07-03 (I think), this unconditionally pushes mark.

It then uses track-mouse to watch for further mouse events.
If at the end, point has not moved and the last event was
mouse-set-point or mouse-set-region, it deactivates and pops the mark.

Otherwise it assumes it is handling a multi-click event (since
2010-07-05), and does not deactivate mark.

The result is that if you bind mouse-1 to something other than
mouse-set-point, and leave down-mouse-1 alone, then after a mouse-1 click
the mark stays active (unless you specifically deactivate it).

Examples can be seen with image-dired and rst-toc-mode, which both bind
mouse-1 but not down-mouse-1. In both cases, mouse-1 clicks leave the
mouse active. It doesn't seem to matter in either case, but probably is
not intended.

Is the intention that people bind down-mouse-1 as well/instead of
mouse-1, or that things bound to mouse-1 deactivate mark, or can the
multi-click detection be changed somehow to avoid this?