Hi,
I think it would be great if a previously hidden sketch folder would be turned visible when editing a sketch inside this folder.
Currently this is the situation:
To edit a sketch you have to explicitly activate the edit mode via the context menu or a double click (or multiple double clicks if the GUI decides to ignore you for some reason) - so setting the folder visible should be an implicit consequence of this action. After the sketching is stopped the folder could be set invisible again.
OR: Editing a sketch inside a hidden folder could set this particular sketch visible, overriding the invisibility of the folder temporarily.
This way no other sketches would show up and confuse you.