I want to setup a complete virtual machine with its dedicated mouse and keyboard on second screen it works just fine until I wanted it to be wide-screen. ( to completely occupy my monitor) so I installed guests additions which created this problem of the cursor being invisible I guess it installed some USB mouse drivers for seamless mouse switching but I don’t want my host mouse in guest machine. I want to custom install the drivers from virtualbox guest additions so I select the display drivers and other 3d optimizations