Hi, Now GTInspector can inspect objects that use custom Slot definitions. https://pharo.fogbugz.com/f/cases/14741/GTInspector-add-simple-slot-support <https://pharo.fogbugz.com/f/cases/14741/GTInspector-add-simple-slot-support> create a class with he TestSlot (where the ivar lives in the Slot instance and is thus shared over all instances of A): Object subclass: #A slots: { #iv => TestSlot } classVariables: { } category: âPlayground' Inspect A new change âivâ to value (e.g. 5). inspect another "A newâ ==> it should show the value as 5. Thus both reading and writing now is done via the Slot. (as such this require just a very simple change in GT, of course). The GT support of course needs to be improved later: -> we need a view that shows the object âas it really isâ (keep in mind, this object has no VM level instance variable!). -> In the view with the slots they should annotated so we see that it is a slot and can easily navigate to the slot definition -> ⦠I am sure more will be obvious as soon as we use it. Marcus