track off screen by adding future point/track

- Stop track where the pattern start to go off-screen
- change cursor to 'add'
- go to the other frame where you want to add new keyframe.
- shift drag the cursor. The new keyframe will be created and ghost will appear to help to match with original pattern.
- as alternative to the 'shift-drag', i can also set value in the input fields of the 'shift' parameter
- move current positioner to other frame , repeat the 'sfhit + drag' to add more keyframe.

This will add new keyframe to predict future track position.

note :
to add 1 keyframe for next/previous keyframe.
switch to 'add' then drag the X (cross) or any available keyframe CP.