On Tue, Apr 28, 2015 at 5:00 PM, Levente Uzonyi <leves at elte.hu> wrote:
> If there's an error signaled from aBlock, and the default error handler is
> activated (see UnhandledError >> #defaultAction), then the process will be
> suspended (see Debugger class >>
> #morphicOpenOn:context:label:contents:fullView:)
> while it's inside the AccessLock mutex's critical section.
> The (new) UI process will try to display a debugger. To do that, it will try
> to read the values of various preferences, but the suspended process is
> holding the mutex, so it'll wait forever.
> This results in an image lockup, because using Alt+. (Cmd+. on mac) will
> also try to open a debugger.
> This is why aBlock must be evaluated outside of the AccessLock mutex's
> critical section.

Okay, the newer one is probably safer because #at:ifPresent:
*probably* won't get an error, but theoretically it still could,
leaving the image locked for the very same reason.

So Eliots suggestion is sounding good -- why do something like
preferences need to be guarded on access?  It seems not that
important...