Input method candidate windows are hard to read and navigate

I don't use input methods myself and am not completely familiar with how candidate windows get used. However, there are some obvious UI issues with our existing candidate windows which would be good to resolve:

• Light text on a dark background isn't the best for legibility, and can cause issues
• The popovers are quite visually disruptive - partly because they're dark, but also because the presentation is quite noisy. The horizontal orientation windows are particularly bad, because they are constantly moving and changing width.
• In the vertical orientation candidate windows, the candidate characters are not horizontally aligned with the text that has been entered. This makes it harder for the eye to scan down the list.
• When using the pager buttons, the windows can change height and width, so that the button moves away from under the pointer and you have to chase after it.
• If a candidate window is being displayed and you move the parent window, the candidate window doesn't move with it.

Some designs for how some of these issues could be resolved:

The most recent version of these designs can be found here.