Returns a ReactiveValue that updates based on whether this tool is enabled.
Returns true iff the tool handled the event and thus should receive additional events.
Returns true iff there are additional pointers down and the tool should remain active to handle the additional events.
For most purposes, this should return false
or nothing.
Connect this tool to a set of other tools, ensuring that at most one of the tools in the group is enabled.
Override this to allow this tool to be enabled in a read-only editor