I’m looking into this right now. You’re right that there is mention in the readme.txt of SDK Version 1.5 dated 2015-06-12 that
DisplaySize has been deprecated in favor of EyeTrackintgDisplaySize. I tried replacing it but still returns 0.0; worth noting I also had to declare the variable as TX_RECT instead of TX_SIZE2 and calling
success = (txGetStateValueAsRectangle(hStateBag, TX_STATEPATH_EYETRACKINGSCREENBOUNDS, &screenBounds) == TX_RESULT_OK);
instead of txGetStateValueAsSize2,. Though it did compile, at runtime it still returns 0.0 for screenBounds.width and height. I will try upgrading to SDK 1.6 now and will get back to the forum.