Ever since 1.8 there's been this issue where after being in fullscreen mode and wanting to make window mode maximise screen it would grey out the maximise button. But if I launch the in window mode it works. You'll see that the maximise button is greyed out. This has been affecting Windows 10, 8, 8.1 and 7. Please help
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-68754. You can find or add further information on that report.
If you haven't, please search before reporting any bugs, as it's likely that one exists already.