[Libguestfs] libguestfs support snapshot based virutal disk analysis?

Hi dear all: I have browsed almost all architecture of libGuestFs and use it on Fedora 18. It really seems greate! However, 1. No virtual disk (*.vdi, *.vmdk...) based snashot analysis code Current LibGuestFs could recognize and virtual disk format (e.g. *.VDI) and the file syste inside it (e.g. NTFS ), but find no support for snapshot virtual disk. Virtual Machine such VirtualBox will generate snapshot (*.VDI for virtual disk diff, *.sav for virtual memory diff), and these snapshots are always diff towards based virtutual disk. 2. So I missed this feature? Or these feature not supported now? If not support, so does libguestFs will support it in the future? What is the effort or difficulty for this part development? Or you have any other opitions? Thnaks very much for your kind reply. Best regards