Clarion 8.0.8658 / NT 5.37
Using web1 as an example. Note the "MailBoxesControl":

I now delete this control:

I can compile, I can close Clarion and Open Clarion, I can export and reimport the procedure, but when I go to Client Side Reset the delete control is still visible:

None of the deleted controls appear in the generated code, but it annoying when you have a list full of deleted controls.