Hi,
I recently upgraded from VirtualBox 5 to 6 (6.0.8 on Win 10 x64), and I created a brand new VM with Kubuntu 19.04 x64. But I'm unable to resize the display. Actually, resizing the display from Kubuntu's settings works for a split second, then the screen is back to 800x600.
I found a bunch of previous threads advising to make sure auto-resize is enabled, but here's the thing: it can't be enabled, it's greyed-out (I have a screenshot, but apparently I'm not allowed to link to it and it's > 128KB so I can't attach it either...).
Also greyed-out are the "View => VIrtual Screen 1 => Resize to 1234 x 1234" options. All of them, even the one that's checked (800x600)
I also read that I should use VMSVGA as a graphics controller, which is what I do use... I also assigned the max amount of video memory that VB allows me to (128MB only though, it seems low).
Last but not least, I made sure "maximum gues screen size" (in VirtualBox preferences) is set to "None", rather than the default "Automatic".
What else can I change? Everything worked fine in VB 5, as far as I remember :/
Edit: yup, I just downgraded to 5.2.30, and screen resizing works fine with it