Ubuntu – Create the own keyboard input layout

The Keyboard Layout window inexplicably won't allow you to choose more than 4 layouts. However, you can fire up gconf-editor and navigate to /desktop/gnome/peripherals/kbd/layouts and manually add as many layouts as you like.

I don't understand the arbitrary limit in the GUI, though.

I think that David provided a useful hint. ibus-mozc does not seem to provide a GUI for controlling the keyboard layout used together with Mozc, but you can edit the file /usr/share/ibus/component/mozc.xml:

--- /usr/share/ibus/component/mozc.xml.orig
+++ /usr/share/ibus/component/mozc.xml
@@ -16,7 +16,7 @@
   <icon_prop_key>InputMode</icon_prop_key>
   <icon>/usr/share/ibus-mozc/product_icon.png</icon>
   <setup>/usr/lib/mozc/mozc_tool --mode=config_dialog</setup>
-  <layout>default</layout>
+  <layout>jp</layout>
   <name>mozc-jp</name>
   <longname>Mozc</longname>
 </engine>

Or in plain English:

Replace the line

  <layout>default</layout>

with

  <layout>jp</layout>

With that change (and after a relogin), Japanese (Mozc) will always be based on the basic Japanese keyboard layout, irrespective of which keyboard layout you switched from when enabling Japanese (Mozc). Hence you can add e.g. the German layout without it affecting your use of Japanese (Mozc).

HTH