Session history pane - selective clearing

[Davin Church]

The design document says "The content of the session history pane is not editable. It may be cleared using the Session > Clear Session History menu item." However, I will frequently want to clear sections of (incorrect) output off my screen so I can see other (correct) sections together. If this pane is not editable, I can't do that.

Why is this pane not at least partially-clearable?