I have Squeak6.0alpha-17945-32bit.image and don't see this.
I update now for see some new introduce the bug


On 10/05/2018, 05:49, "Stéphane Rollandin" <lecteur at zogotounga.net> wrote:

> Hello,

In the Squeak6.0alpha-17967-32bit image, open an explorer and attempt
> to 
use the "browse class" item. You'll get a DNU from PluggableTreeMorph on
> 
#browseCass.

It works in an inspector, though.

Stef