After an event bubbles to the root box of the scene (and bubbles to the parent
scene it is asked to), we will update certain information (for example, who is the
current box being pressed, who is the current box being hovered, who is the current
open pop-up box, who is the current focused box, etc.) and do certain tasks (for
example, drag and drop, trigger access key and accelerator key, etc). If any box
reacts to the event and calls eventObj.preventDefault() when the event is bubbling
up, we will NOT update those information and will NOT do those tasks after the event
bubbles to the root box of the scene.
eventObj.preventDefault();