Feature idea: Entering arbitrary Unicode characters

[Tor Lillqvist <tml iki fi>]

I wrote on the gimpwin-users list:
 > But, I think we should realise that using Alt+0nnn is not a "good"
 > solution. The characters available cover only the current
 > codepage. (Or the codepage associated with the current keyboard
 > layout, or is that the same thing?)

 > We really need some similar way to input arbitrary Unicode
 > characters using their Unicode value in the four-digit hex
 > notation. (But implemented in GDK, or perhaps GTK.) This isn't only
 > for Windows, but would be very useful on all GTk+ platforms. I'll
 > take it up with the GTk+ developers. If anybody has a suggestion
 > what would be a suitable key sequence to enter arbitrary Unicode
 > values, please tell us. (Perhaps some other system already has this
 > possibility, and one could use the same sequence)

I think this feature would be very useful. What would be the "correct"
place to implement it? In GDK, at the low level event handling? In
GTK?

What key sequence would be a good choice? Presumably some
meta-cokebottle keys followed by (or chorded with) the Unicode value
as four hex digits? (OK, it might be a bit hard to input them on
keyboards where the latin letters A--F are hard to get at (are there
such?), but you never see Unicode values in decimal anyway, do you?
Thus I think four hex digits is the only reasonable choice to indicate
Unicode values.)

Does anybody know how other systems handle inputting arbitrary Unicode
characters quickly from the keyboard (without using any GUI)? One
would think that this feature already exists somewhere. MacOS X? BeOS?

--tml