Getting VBox Guest Addtions for Android x86

Just disable "mouse integration" in Host Machine tab.

ref. https://code.google.com/p/android-x86/issues/detail?id=341#makechanges

Android is not a supported guest OS according to Sasquatch, a moderator at the VirtualBox forums, at https://forums.virtualbox.org/viewtopic.php?f=9&t=42240

Android is not a supported Guest OS, so there are no GA. Also, it doesn't meet the requirements for guest addition support: you can't install support packages for the kernel to make kernel modules. At least not that I am aware of.

The VMs provided by Genymotion have theses features integrated (at least for the mouse pointer capture/release which is automagically done).

So I don't have the solution, but it's at least completed on a commercial software providing VirtualBox-compatible images.