This function is used to set the time within which a pair of touches must be rotating in a consistent direction for a Rotate Start Gesture to be triggered. The time is measured in seconds and has a default value of 0.16s.IMPORTANT! Currently for a 60fps game you can only set this to a maximum of one second otherwise no rotations will be detected. This will increase for a lower framrate, for example a 30fps game can have a maximum time of 2 seconds.
if gesture_get_rotate_time() != 0.1
The above code checks to see if the rotate time for gestures is set to 0.1 seconds and if it is not it sets it to that value.