wow that is tiny. After reviewing the code that adjusts the window position for the second time I was unable to find anything that might explain this behavior. Thats when I realized I should check the source for 3.0 build 1045, I see some slight changes to the way the window is sized compared to the latest beta.
You may want to give the beta release a try and see if it solves your problem, at least we'll know and if not hopefully we can get this solved for the final.
https://oss.azurewebsites.net/download-beta.php