If your problem or request can be applied to Google Japanese Input on
Windows and Mac OS X, please consider reporting it to the Google Japanese
Input product forum rather than Mozc's issue tracker, where we want to
handle Mozc-specific issues only.
https://groups.google.com/a/googleproductforums.com/forum/#!forum/ime-ja

What steps will reproduce the problem?
1. Set up dual monitor, with different resolution (1680x1050 and 1920x1080) 
with the top aligned, IE so there's a gap on the bottom of the 1680x1050
2. Fullscreen gnome-terminal on the smaller monitor (1680x1050)
3. Run irssi, input should be on bottom row of gnome-terminal
4. enter ibus-mozc and type something, say "わたし" then press space to 
change it to kanji then use the up/down arrows to bring up a menu for selecting 
which one to convert to.
5. The menu is displaying below the input field, we can now only see a couple 
of pixels on screen, the rest is off screen. (This happens with both the ibus 
provided dialog, *AND* the mozc custom dialog. I think this is an ibus issue 
but if it also happen with the mozc custom dialog...)

What is the expected output?
The expected output is for the menu to display *above* the word being 
converted, this works properly on the (1920x1080) monitor, so it seems to 
indicate some form of xinerama issue with ibus menu dropdown.

What do you see instead?
The menu/selection hanging off screen