id summary reporter owner description type status component version resolution keywords cc guest host 16347 Full screen mode broken on MacOS hosts with Guest additions 5.1.4 and later agodfrin "I am running VBOX on MacOS. I am tracking both MacOS versions (currently on macOS Sierra (10.12.2), and VirtualBox versions (currently on 5.1.12). I use all my VMs (Linux) in full screen mode Last september I had upgraded VBOX to 5.1.4. I then upgraded the guest editions to 5.1.4 as well As a result, full screen mode stopped working: the VMs no longer occupied the whole screen, but only part of it. Luckily I was able to go back to the previous guest additions (5.0.20) and got full screen back to working as usual. Today I upgraded VBOX to 5.1.12 and tried again upgrading the guest additions to 5.1.12. Same effect: full screen broken the same way (full screen no longer occupies the entire screen). Again, downgraded guest additions to 5.0.20. What seems to happen is that the guest additions somehow no longer automatically match the resolution of the VM screen to the resolution of the host display (1280x800). I also see differences in the View menu. With guest additions 5.0.20, the View menu is like this: - Full Screen Mode (Host+F) is checked - Auto Resize Guest Display is checked. - Scaled Mode (Host+L) is unchecked With guest additions 5.1.4 and later: - Full Screen Mode (Host+F) is checked - Auto Resize Guest Display is checked but greyed out - Scaled Mode (Host+L) is unchecked but greyed out " defect new other VirtualBox 5.1.12 Linux Mac OS X