We have in Roundcube a feature which adds odd/even classes to table rows. This feature is currently buggy. Doesn't work as expected for threaded view and for row replacement actions e.g. in folder manager.
Fixing these bugs can be expensive and the way how the fixes would be implemented will be probably an expensive javascript operation (iterate over all rows of a table, detect and change class).
This feature is not used in default skin.
That's why I think we could remove this feature. Does anyone using it in custom skins?