How to re-size a virtual box disk

I found today that my windows vm in ubuntu was completely out of space. I tried to find some resize option in the UI but I was unable to find anything. So reading the doc for the command line I found this:

cd /your/path/vm/
VBoxManage modifyhd mydisk.vdi --resize 50000

The size that you specify is in megabytes.

Cheers!