[squeak-def] - worldState - error in object morph

On Mon, Nov 20, 2017 at 02:46:06PM -0800, Chris Cunningham wrote:
> Hi.  Not sure if this is related to the recent rash of world/morph changes,
> but if you open "object(o)" on the desktop, and choose Multimedia, you get
> an error not understanding object not understanding #displayWorld:submorphs:
> [image: Inline image 1]
> worldState in PasteUpMorph is nil at that point.
>
> Thanks,
> cbc

I think that I have located the bug, though not fix.

I do not think that it is related to the recent global World changes,
instead it is related to initializing the Thumbnails dictionary in class
PartsBin. The bug is present only when the docking bar preference
'Show Sugar navigator bar' is false, and only when first initializing
the dictionary.

I went back to an older image (Squeak6.0alpha latest update: #17457) and
found that I can reproduce the bug as follows:

- Set preference 'Show Sugar navigator bar' (in category 'docking bars' to false.

- Clear the Thumbnails dictionary by evaluating "PartsBin initialize".

- Open a ObjectsTool with objects (o) in world menu.

- Click the Multimedia button.

To make the problem go away (by successfully initializing Thumbnails one time),
enable the 'Show Sugar navigator bar' preference, and then click Multimedia.

From then on the Thumbnails are initialized and the preference setting causes
no further problems.

I think that the actual failure happens in EventRecordingSpace>>initialize at
the end of the method where the preference is being tested, and the failure
happens in the course of adding flaps. I have not tried to fix it, but perhaps
someone familiar with this area can have a look at it.

Dave