Re: Issue with rectangle mouse selection

[Mattias Engdegård]

28 nov. 2019 kl. 11.00 skrev Ergus <address@hidden>:

> Trying the just new added rectangular mouse selection first, I'll say:
> this is a very nice feature, very very thanks for it Mattias.

Thanks for trying it, and for reporting your findings!

> 1) In tui interface the rectangle region is not highlighted during the
> mouse movement, just when the mouse button is released.

That's odd --- it seems to work with some terminals (after enabling 
xterm-mouse-mode).
Terminal.app and Gnome Terminal are fine, but Xterm exhibits the behaviour you 
describe.
I'll investigate.

> 2) In gui the rectangle limit and the cursor position are in different
> positions. This is more evident when using tabs indentation or crossing
> empty lines.

That's a behaviour inherited from the cursor-based rectangle marking (C-x SPC), 
which is the underlying mechanism. Ordinary linear region selection actually 
works the same way: the region includes the starting point but excludes the 
cursor position.

The only difference is that with rectangular selection, the mouse tracks the 
rectangle corner, not the cursor. This was done partly to get better behaviour 
when selecting up to the right margin, and partly because it felt visually more 
pleasing. It also makes it easier to select 0-column wide rectangles, which are 
occasionally useful, whereas zero-sized linear regions are not.

However, because of how the our eye-hand coordination works, a small offset 
matters very little in practice: the hand will automatically move to set the 
desired selection from the immediate visual feedback without the user 
consciously thinking about it.

By the way, I'm still not quite happy with the standard binding (C-M-mouse-1); 
it was a weak compromise. If we could dislodge the squatters of the Meta, 
Control or Shift bindings, I'd much rather use one of those modifiers.