Patch for thumbnail update in layerbox

[Cyrille Berger]

On Sunday 19 September 2010, Boudewijn Rempt wrote:
> On Sunday 19 September 2010, Dmitry Kazakov wrote:
> > I think adding parameters is the worst thing that we can do here =(
> 
> Maybe it would be better to bite the bullet & not use the locked system to
> hint for updates, but add a signal updated() to KisBaseNode that can be
> emitted by tools when they are done.
Yes I quite agree. Sounds like it is a workaround, that abuse an other 
workaround. The reason systemLock was added is because we didn't had a system 
to queue actions.

This is why I also agree with Dmitry that systemLock should disappear one day.

It should be replaced by a list of action that need to be applied on a node, 
and in a thread, the first action of that list is applied in thread, and tools 
only add new actions to that list. And some tools (or paintops) that needs an 
empty list (think the duplicate op) would simply be locked or prevented to 
paint (and show the "blocked" cursor).

We basically have all the bricks to implement this with the ThreadApplicator 
framework, and the action recorder to provide the actions.

-- 
Cyrille Berger