Hi @simmys and thanks for your query. I am afraid that the Core SDK (nor our other offerings) have a blink detection algorithm implemented, meaning this is something you will have to create manually using a combination of validity filters and timing loop (<400ms).
We do have further samples which might help you get started quicker available @ https://github.com/tobiitech/core-sdk-docs
In terms of gaze leaving the screen, the un-normalised coordinator (0,0 -> 1,1) will be outside the range both in the negative and positive if the user looks outside the screen, but eyes are still ‘trackable’ to a detection algorithm within your program should resolve that.
Please let us know if we can provide any further information. Best wishes.