Qemu 2.0 Windows guest - mouse stops working (vnc) when using usb-passthrough

I finally found a fix for this bug/problem! It is in fact a bug, but I don't know whether it is a Windows bug or a Qemu/VNC-bug. After connecting a massive storage device to the Windows 8.1 guest, the mouse stops working because it goes into a sleep-state.

This bug can be fixed by going to WIN + X, Control Panel, Devices and Printers. There you can see the QEMU USB Tablet which is a tablet/mouse device used for the VNC-mouse to work on the guest. Right click it and select Properties. Next click on the tab Hardware. Normally you should see two devices (based on what hardware you assigned to the guest), HID-compliant mouse and USB Input Device.

Now select the USB Input Device and click Properties at the bottom. This will open a new window with the device's properties. Next click on Change settings (you'll need Admin.-powers for this) and go to the Power Management tab on the newly opened window. There you should see an option ticked with the following explanation: Allow the computer to turn off this device to save power.

Unchecking that option and pressing OK solves the problem. This whole route can be done with keyboard-only (as the keyboard still works). Press ENTER to open things, use TAB to move to different menus and press SPACE to simulate a single mouse-click (for unchecking the checkbox).

I still can't find any related topics of people having the same issues as I did, but it is a bug and should be fixed. I have no idea if it is Windows or Qemu related and I hope that the Qemu-team can further inspect this.