How do I add non-breaking spaces in custom properties' value fields?

[HoffArt]

I type Ctrl-Shift-Space and nothing happens.

[librebel]

if you are on Ubuntu you could try: CTRL+SHIFT+U then 00a0 and then enter

[HoffArt]

Thank you for your suggestion but I’m on Windows 7.

[librebel]

on Windows you could try: ALT+0160

[HoffArt]

Thank you for your suggestion, but unfortunately it doesn’t work either. To my mind, Ctrl-Shift-Space should work, the same as anywhere else in the content areas. Where can I log this as a bug?
Thanks.