When I make the roundcube application window a bit smaller, the "filter"-text comes on top of the action-button. The action-button is still accessible, but it looks a bit messy (just like my english I suppose). My windows toolbar sits on the righthand side of my screen by the way, thus explaining why I have a smaller window for applications ...
The default skin is designed for a minimum resolution of 1024x768 anything smaller than that and things will start to look odd. I guess the best solution is to wait until the skin documentation is done and make one from smaller screen.
Thank you for your reply. It's really not a big deal of course, and most people won't even notice it. If you are aware of this situation, it's ok for me.
PS : in the English language, the filter-box is smaller, due to the shorter list-items (in foreign language, these words can be a bit longer ...