Resolution issues across 2 versions and the test build

[MachinaeWolf]

On version 5.1.2 of virtualbox and even the testbuild even with guest additions installed and after running vboxmanage controlvm win2008server setvideomodehint 1366 768 60 it will not change the window size beyond this . If I try seamless mode it just shows a black screen with the vbox controls at the bottom and the same thing happens with the fullscreen mode. The only mode it doesn't do that in is the regular one that's too tiny for me to use or in scaled mode. On version 5.0.24 I can use the VM in regular mode fine but it also has the same issues on seamless mode and fullscreen.

Specs: slackware 14.2 64bit i5-2430M processor intel integrated graphics (sandybridge/hd 3000) 8gb ram

guest OS: windows 2008 server