How to lock cursor to full screen area of program running in VirtualBox guest?
 

I have a VirtualBox guest OS that runs a low resolution (lower than resolution of host) full screen program. This is how my screen looks in full screen (host) VirtualBox: https://postimg.cc/hhq99SHs

I want my mouse cursor to be locked inside white area, because now it doesn't.

Tehnical details:

Host system is Slackware64-14.2
Guest system is Windows 7 x64
Vanilla VirtualBox 5.2.20 from Oracle
Guest additions are installed

If you go to the Input menu at the top of the host's VirtualBox window, you can hit the option to turn off "Mouse Integration". Then you can lock or unlock the cursor with the right Ctrl key (although the exact lock/unlock key can be customized)