Hello Biffi,
try this:
1. create computed read only extended attribute "Active Diagram Flag" with the Get method:
Function %Get%(obj)
Dim tab, found
found = false
for each tab in ActiveDiagram.Symbols
if tab.object = obj then
found = true
exit for
end if
next
%Get% = found
End Function
2. Add the extended attribute into List of tables with operator "=" and expression "true"
3. Enable filter on the List of tables
Vlasta