This is a new app for managing virtual machines and QCOW2 disk images created by Virt-Manager for Qemu/KVM.

Apex provides a GUI for creating overlay files (“undo” disks) for the base disk image. When the overlay disk is attached to a VM, the VM sees the combined data from the overlay disk and the base image. However, changes made by the VM are written to the overlay disk instead of the base image. These changes can be committed (merged) to the base image, or discarded to reset the overlay disk.