System Information

OS: Linux venus 6.8.0-62-generic #65-Ubuntu SMP
i3 Window Manager Version: i3 version 4.23 (2023-10-29)
VirtualBox Version: 7.1.8

When creating a new virtual machine in VirtualBox, the "Mini Toolbar" option is enabled by default in the VM's settings. If you then switch the virtual machine to fullscreen mode while running under the i3 window manager, the screen goes completely black and becomes unresponsive. Keybindings stop working, and the system appears frozen.

This issue has persisted for quite some time and is still present in the latest i3 version 4.24. Fortunately, the problem can be resolved by disabling the Mini Toolbar in the VM's settings:
Right-click on the virtual machine > Settings > User Interface > [Uncheck] "Show in Fullscreen/Seamless".

Although the workaround is simple, this bug can be quite frustrating—especially for users unfamiliar with i3 or VirtualBox settings. Since the Mini Toolbar is enabled by default when creating a new VM, many users may not understand why fullscreen mode breaks in i3, leading to confusion and unnecessary troubleshooting.