bug#38013: [PATCH] Rectangular region selection with mouse

[martin rudalics]

9> Competing mouse bindings are:
>
> Meta: secondary selection

The meta combinations are bound to the secondary selection in a very
elaborate fashion and should be left alone.

> Shift: mouse-appearance-menu (mouse-save-then-kill for NS)
> Control: mouse-buffer-menu

I have no idea why these are bound to down events in the first place.
I would reserve S-down-mouse-1 for extending an existing selection and
provide C-down-mouse-1 for rectangular selection.  Some programs allow
C-down-mouse-1 to provide non-contiguous selections which we then
could accommodate easily by checking initially whether a selection is
already active.

> B. Combined modifiers (Shift-Meta etc). Less ergonomic; there may be platform 
restrictions.

I'd consider these as viable alternatives.

martin