I've started implementing @jmcouffin 's wish from linkedin, and I'll try to track the progress here.

MVP

• isolated context using a modeless window
• use view selection from Project Browser
• show only on views with section box, use the section box for extents
• show cut plane
• show top, bottom, view depth planes
• handle DocumentChanged event to update geometry (section box, view range changes)
• finalize UI

Further directions

• convert the tool to a smartbutton
• optional side faces
• edit view range directly from the ui if it stays modeless