MVC scheduling broken in trunk

Something is out of whack with MVC control scheduling in Squeak trunk.
I am guessing that it may be something related to some earlier process
scheduling changes, but I can't spot what is going wrong. Here are a couple
of scenarios that illustrate the problem. Can anyone point me in the right
direction to find the cause?

Scenario 1:

  From an MVC project, evaluate:

    ProjectView open: MVCProject new.

  No window opens, and the image will not respond.

  Now do an <alt><period>, and Squeak exits with "scheduler could not
  find a runnable process" on the console.

Scenario 2:

  In an MVC project, do <alt><period>. No debugger window opens. Do
  another <alt><period>, and Squeak exits with "scheduler could not
  find a runnable process" on the console.

I first noticed this issue some time ago when I was checking low
space interrupt handling (which is broken for the same reason I guess).
Today I was looking at a problem in the MVC open->mvc project menu
and see the same sort of symptoms, so I think this is an issue that
has been in trunk for a while, most likely prior to any of the recent
Project refactorings to separate MVC and Morphic.

Thanks,
Dave

David T. Lewis wrote:
> Something is out of whack with MVC control scheduling in Squeak trunk.
> I am guessing that it may be something related to some earlier process
> scheduling changes, but I can't spot what is going wrong. Here are a couple
> of scenarios that illustrate the problem. Can anyone point me in the right
> direction to find the cause?

I think the problem comes from a debugger issue, specifically Debugger
class>>openOn:context:label:contents:fullView: where it says:

        WorldState addDeferredUIMessage: [
                "..."
        ].
        process suspend.

Since there is no drain for the deferred ui message and the process is
suspended no debugger gets opened.

Cheers,
    - Andreas

On Sat, Oct 31, 2009 at 10:27:14PM -0700, Andreas Raab wrote:
Ah, yes, thanks for the lead.

Dave