Whether it follows the cursor, waiting for the click that places a plane (armed by a tool, or Ctrl held)
Whether it was armed by SectionPlanes.startFaceTouchOff (a mode a user interface names), as opposed to the Ctrl preview
Disarm it without placing a plane
Called with armedByTool whenever it changes
The unsubscribe
Whether it follows the cursor, waiting for the click that places a plane (armed by a tool, or Ctrl held)