Extend vdi disk on VirtualBox with Windows 7 guest

When we install an OS for a VM it is possible that we estimate a size that now is not enouth and the disk is little for our working needs. With Windows 7 guest it is possible to extend the partition:

1. Create a new vdi disk with desired size
2. Clone: VBoxManage Initial.vdi New.vdi --existing
3. Change SATA-0 port disk with new vdi file
4. Start VM
6. Control Pannel > Admin Tools > Host management > Storage > Disk Management
7. We can see our disk with not assigned space
8. Click right button in primary partition and extend

New disk is new available free space to work.