This is a GUI for virtual pc emulator "qemu". But it is not for configuring devices or starting qemu, no it is for changing media, reset the vm, making screenshots, and so on. And this at runtime.
If you are a user of one of the configuring GUI's, just change the path to qemu to qemuctl and it work.
So, if you are developing a configuring GUI for qemu and you want qemuctl firing up with your GUI. This can just add a suspend screenshot to your GUI like you would see in vmware, then launch qemuctl instead qemu. Now qemuctl will do the job launching qemu. Now drop me a note and you are on the supported configuring GUI's list.