During the promotion process, the Getting Started doc says:
"Click on the right side of the AnchorPane node to enter the fx:id mode".
Doing this, if one click at the middle of the free space on the right of the AnchorPane, nothing happen. One need to move the mouse very closely of the AnchorPane label so that a small grey rectangle appear. This make the edit mode very difficult to discover. This grey rectangle should take the full width available, so that clicking at any point on the right of a component, the edit mode is enabled.