In GTK+ Linux environments Unicode input can be achieved using this method[1]:
Enter Ctrl+⇧ Shift+u, release, then type the hex digits, and press ↵ Enter (or Space or even on some systems, press and release ⇧ Shift or Ctrl ).
While this is not universal (KDE apps, terminal apps, and other use other methods), this is how it works out of the box in Ubuntu, Fedora, and a few others which make most of Linux shipments. Would it be possible to support such an input method?
– nachokb
[1] source: Wikipedia