Checks if the thread is currently busy executing a script
code in result of Start or Execute methods.
variable = object.Busy
Returns Boolean result. True means the thread is busy, False the
thread is not executing script at this moment.
Except for checking for completion the Busy property can be used to
check if the thread is free and can be used to execute a new
operation. See also Wait.
Applies to: COMScriptThread