Of-course I know devices like these serve a purpose and I don't want to ruin the joy of a new gadget, but just so that readers find out the options, here are the ones I currently use:
In general, I have this keyboard and touchpad. However, it is an app that I downloaded onto my tablet. This is an iPad
but I think it will work with any type and also smart-phones.
1. MobileMouse (was AirMouse). Exactly like the OP device except you don't need a dongle but use a driver on the computer instead.
2. Splashtop2 goes way beyond this and provides a remote desktop
, i.e. you get the keyboard, touchpad and the display itself so you can work out of view of the computer screen
Best of these options is that they are cheap
or even free and the range is only limited to your wifi
router so you can make it the whole anchorage which can be useful with Splashtop.