Make sure that View Auto resize guest display is enabled checked. First, make sure you are not in fullscreen mode: i. This constraint is now stored in the windows registry somewhere, so you need to go through a few hoops to get around it. The problem is that your Windows guests think that the virtual monitor isso they are helpfully disallowing any display modes that use a widescreen ratio. I'm guessing that is close to the full height of your display. It would be nice to know its display size. Though you have not said so, I'm going to guess that your host PC has a widescreen monitor. Any ideas? Do you actually mean that you can resize, but you can't go larger than x? If yes, then I had that problem with VirtualBox 4.
The guest additions are installed! With version 4. The max resolution is x Windows doesn't let me choose any higher resolution.
In both guests it is no longer possible to have an automatic resizing of the guest resolution.
