[xmonad] Slow reload

[Yitzchak Gale]

When xmonad needs to recompile xmonad.hs during
a reload, that can take time. My machine is a little slow,
and sometimes it can be under load.

Really weird things can happen In that situation.
xmonad seems to be in limbo while the compilation
is happening, before the red border flashes.

So, for example, let's say I press mod-Q again
during that time. I'm using KDE, with Windows as my
xmonad mod key. With xmonad in limbo, KDE gets the key
press. If the current window happens to be a Konsole,
for example, that causes the mod key to stop working
even after the xmonad reload finishes. Very embarrassing!

Seems to me that xmonad ought to do the following
on reload:

1. Pop up a floater that says "xmonad reloading..."
2. Compile the config module in the background.
Meanwhile, keep catching xmonad key events but
ignore them.
3. When the compilation finishes, dismiss the floater
and restart with the new config.

Is this possible?

Besides key presses, other interesting things can
happen during a reload. There are probably numerous
race conditions lurking here.

Thanks,
Yitz