virtualbox.org

I have a MAC machine and I have installed the latest virtual-box 5.2 and I have a kubuntu virtual machine running having updated guest additions.
When I press green button of the Virtual Machine window to maximize it to fullscreen then the screen gets maximized but the Vurtul Machine inside doest get the full screen.
It just acquires the half portion keeping remaining in black background.
Then again I resize get off from fullscreen by pressing the same green button.
Then again I press the green button to get full screen and this time Virtual Machine gets the full screen .
So my question is why it doesn't work for first time?

dhany wrote:So my question is why it doesn't work for first time?

You'll have to ask the Qt people/Apple people. It's a known issue with this sort of 3D behavior. Not a known workaround at the moment, instead of 1) min/max size, 2) hide/show app.