bug#37700: 27.0.50; undo mouse-drag-and-drop-region ineffective

[Mattias Engdegård]

Tak Kunihiro wrote:

> On revision of writing, I often want to move a sentence around to fit
> into right place, without loosing the sentence from sight.  Most of the
> time I cannot relocate the sentence to the best place by single
> drag-and-drop operation thus I want to maintain region active.

Thank you, very much my experience.

> I found that I did not notice problem pointed by Mattias because I
> assign `undo' by `redo+.el' to C-/.

Ah yes; apparently, region handling is mentioned in a TODO comment in redo+.el 
but nobody has bothered to implement it. Looks like the demand isn't there.

Martin Rudalics wrote:

> I think that we should provide an option to not enable the region
> after dropping and maybe even make it the default.

That would seriously degrade usability of the drag-and-drop feature. Selecting 
the text at its final position both highlights it, and allows the user to drag 
it again or do other region-related operations. (Other editors work the same 
way.)

This behaviour is definitely more important to the drag-and-drop user than the 
region-confinement of undo.

Eli Zaretskii wrote:

> So perhaps a better way to resolve this situation is to teach 'undo'
> about drag-and-drop, so that it doesn't undo selectively immediately
> after drag-and-drop?

Maybe --- can it be done within the current 'undo' framework, or would 
drag-and-drop need to be special-cased? Did you have a particular approach in 
mind?