I'm a user of Ned Konz's lockdown package to achieve what I would call 
"Kiosk mode": complete disabling of everything in the Squeak UI except for 
what is allowed by "my" morphs. This works fine under 3.8. Today I tried it 
on 4.3. It mostly works -- no world menu, halos don't come up, but on Linux 
when I right-click (I forget which color button that is, I never did learn 
Squeak mouse button colors ...) this menu *does* come up. For the World 
this allows showing the docking bar, and from there you can get all kinds 
of things. So this is a hole.

Has anyone run into this? Is there a fix?

Ned, you out there? [Trying Bcc ...]

-Thanks in advance, Jim