DaveAhrendt:
There's something weird going on with 1.8.8 preferences. As previous poster stated the fullscreen is wonky but so is the opening of the last sketch used. It now opens with a empty sketch where in 1.8.7 it opened the last used. Reverting back to 1.8.7.
Thanks for reporting this. There is now a proposed fix:
Test builds are available at the link above if you want to try it out.