okay. I can see how that works. But I can't work out the display logic.
Selecting... Collections-Streams > ReadWriteStream > inherited methods
�� asBinaryOrTextStream(PositionableStream) is shown normal
�� asZLibReadStream(PositionableStream) is shown grey
Can you explain?

It's easy. Class extension is shown with grey and #asZLibReadStream is from Compression package.

Actually this logic is a bit different. If method not belongs to selected package (from package view) then it will be shown with grey.��

It is current logic of Nautilus.