Workaround for extension being disabled on screen lock

[Tim Cuthbertson <tim gfxmonk net>]

Hi all,

The fact that all extensions have their disable() method called when
screen lock starts (and enable() called when the screen is unlocked)
is new to me, although it's presumably been around a while.

For my shellshape extension
(https://extensions.gnome.org/extension/294/shellshape/), this
behaviour is really inconvenient, since it cleans up after itself
thoroughly - when you come back from the lock screen, all of your
wokspace layouts and window dimensions get reset to the default
layout.

Is there any way for an extension to declare that it is safe to leave
running during screen lock? In shellshape's case it wouldn't interfere
with the lockscreen at all, although I don't know what the rationale
is for disabling extensions so there could be another reason for this
behaviour.

Here's the github issue link on my extension, if anyone is interested:
https://github.com/gfxmonk/shellshape/issues/107

It seems like I'm going to have to try and save the extension's state,
then restore it later. But that's quite tricky, as in the general case
there may be a huge number of differences between the last state and
the current one (workspaces changed, windows resized, moved, or
changed workspaces, windows added / closed / minimized).

Any ideas appreciated,

Thanks
 - Tim.