I tend to use Ctrl+Shift+Alt for my customized system-wide keybindings.
When I tried Ctrl+Shift+Alt+U it printed an underscored u and waited for more keyboard input!…
Some keys were accepted and some were not…
eg. Numbers were accepted and they too were underlined, but only a few keys allowed me to break out.
I then tried Ctrl+Shift+Alt+U immediately followed by Ctrl+Shift+Alt+E.
This produced an unprintable hex 000E(?) and broke out of the loop…
The unprintable character got me thinking that this may be Unicode related.
If so, how so? What is happening here?
Is this underscored u a trigger for an Input Method Editor?
This behaviour occurs: Here (as I type), "gedit", text-edit fields… (but not in the Terminal)… and "gvim" reported "pattern not found"…
Best Answer
Ctrl-Shift-U is the short-cut to start entering a full unicode character by hand. For example, here I've typed: Ctrl-Shift-U 0 0 b 0 enter to get the degree symbol: ° which is unicode 00b0. Here is 2665, the heart: ♥
For a list of unicode symbols start here: http://en.wikipedia.org/wiki/Unicode