If anyone is reading this as a reference to install virt-manager I found one more pretty important dependency, "usbredir", it's an optional requirement for qemu so you can use a virtual machine like in vmware or vbox, in other words without it you cant even see the vm, the screen wont work and you can't connect any usb devices to it either.
If you were like me and didn't compile it in during the initial setup unfortunately I had to not only "reinstall" qemu but the entire build queue for virt-manager so make sure you use that package too, if it's installed the slackbuild for qemu will auto detect it and compile support for into qemu and whatever else requires it (virt-manager maybe idk?).
so this should be the build queue now for virt-manager and don't forget to uninstall slackware's netcat package nc:
EDIT: this is a nice guide on how to use and configure virt-manager for use from redhat. https://access.redhat.com/site/docum...llation_Guide/