First off for troubleshooting reasons why the mouse cursor may be unstable, it could be you need to adjust the distance between your eyes and the Tracker, you could try re-calibrating through your Tobii software. ( For me I’ve found A distance about 24″ with the tracker just below my eye level works great ) other issues that could cause this could be light interference from an open window, or perhaps something reflective which can shine back at the tracker also causing interference.
As for the IRIS software itself, In your ‘Advanced’ tab I recommend setting your ‘Steadiness’ slider all the way up, and the ‘Saccade Threshold’ to 3/4 up, which will improve stability significantly.
I know exactly what you mean about not being able to access things behind the interactor, There seem to be a few pitfalls in IRIS that can make it a bit difficult to use sometimes. However there is a certain order of doing things that should avoid these problems.
So when making an interactor I feel it’s important to first set the opacity to something you can see through, in case you get stuck.
Then to create an interactor that spans the entire screen, what I recommend doing is: set your opacity to be see-through, then ‘Lock’ the interactor.
To edit the position and size of the we’re going to use XY and Width/Height boxes, First set your X and Y both to 0 Which should put the interactor in the top left corner of your screen. Next we will do sizing for the interactor, For example, my monitor resolution is 1920 x 1080, so what I will input is 1920 for my width and 1080 for my height.
After doing this your interactor will now be correctly set for your monitor resolution( you may encounter a strange issue where the interactor is not displaying correctly and appears ‘out of position’, You can disregard this as it’s just a bug. The next time you restart the program and look at it again you should see it’s in the correct position )
After everything is set with position and size, you can go to your ‘Action’ tab And set the action type to ‘FPS View’ And be able to edit all of the curves From here to achieve the sensitivity and dead zone to find what feels right for your particular game.
( Be sure to have set a hotkey that will ‘Pause all interactors’ Because it can be quite easy to get stuck in FPS mode )
I hope some of this this will help you out, I will also send you a private message with my email, if you’d like to speak further about this and more solutions I’ve discovered since my original post. I would also be very interested to hear more about the things you use in your personal setup as well.