The following properties are called variables to differentiate them from the system constants properties, which should never be reassigned. Except for contextmenuEnabled the state of these properties is handled by the system, and you don't normally need to specifically set them.
Boolean; initial true. If false it allows to switch to a custom context menu, or to simply disable the browser's context menu. Learn more in the CUSTOM CONTEXT MENU section of the Tutorial.
Object reference; initial null. Prevents any action on the interface if a preemptive dialog is open.
Boolean; initial true. Prevents selection on mousemove event.
Boolean; initial false. Prevents selection on mousedown event.
Boolean; initial false. If true it cancels selection on mousemove event.