Why the changes to the 18.04 desktop?

[Paul Smith]

On Mon, 2020-10-19 at 11:32 +1100, Owen Thomas wrote:
> I would like to be able to add Alt-Space-C as a shortcut, but it
> appears this cannot be done because it uses a combination of two
> character keys as well as a keyboard control key. Not happy at all! I
> would think that so long as the keyboard shortcut contains at least
> one keyboard control key, it shouldn't matter how many other keys are
> desired.

A key on the keyboard can either be a modifier key or a non-modifier
key, but it can't be both.  A modifier key doesn't have an action
associated with it: it waits for another keypress to appear.  I'm sure
you don't want to turn either SPACE or C into a modifier :).

It's basically impossible to press two non-modifier keys at exactly the
same instant (in computer time).

That means when you press Alt followed by SPACE and C, the computer
will see a two-key combination: either Alt-SPACE Alt-C or Alt-C
Alt-SPACE.

The only way Alt-SPACE-C could work as a 3-key chord is if either you
defined a key combination of Alt-SPACE as a modifier (in which case you
couldn't use it as a separate keypress, which many of us, especially
Emacs users, would flip out about!!) and were careful to always press
they keys in order Alt, SPACE, C; or the computer had a built-in pause
after the first Alt-modified key was pressed to wait to see if another
key was pressed, to create a 3-key chord... such things are possible
(for example, screen sessions do this), but most people find them
extremely annoying.  There's always an argument about how long is
"long", with the people who want to use the key Alt-SPACE and have it
react immediately, versus those who want the system to wait longer to
allow the third key to be pressed.

In general, it's just a bad UI and I'm personally glad it's not
available.