Some clue here:
https://social.msdn.microsoft.com/Forums/vstudio/en-US/11476c2d-8ccc-4af0-b94c-7ddf674a9974/bluetooth-hid-mouse-in-wec2013?forum=winembmngdapp
It says that:
"While this applies to CE 6, take a look at
https://msdn.microsoft.com/en-us/library/ee496018(v=winembedded.60
).aspx. It has a note that states "A Bluetooth mouse is not supported in Bluetooth HID mode. "
So, I'm assuming that Windows CE 6 does in fact support bluetooth HID, but not sure about mouse as it says it doesn't in the above link.
The Sigmarion 3 has a separate HID driver that allowed a lot of USB HID stuff, but I don't know much about bluetooth HID on Windows CE devices.
-stingraze