I've been working on the colour themes side of yWriter all day, and I've managed to include the final elements which refused to obey their overrides. (tab headers, menu separators, etc.)
This version has two updated themes (dark_updated and grey_updated) as well as 'light'
The new default colours in 'dark_updated' and 'grey_updated' are much easier on the eyes, so I recommend using these instead of the old ones. (the old ones are missing some entries anyway.)
If you're using Dark or Grey now, or your own design, there are several new entries you'll need to define. These are Tab control colours, list header colours, and various list selection colours. Until you do, the UI might look a bit odd.