Unreadable text because of transparent background

I love the tooltips that show detailed information on some items, that prevents from cluttering the main text in dialogs, and in the UI in general.

But here is how it gets because of the transparent background, it's unreadable. I set the "Solid HUD Background" option (solid background behind the in-game user interface), but that didn't change this behaviour. Some options are in the wrong category, such as the tooltip delay and the solid background, but I haven't seen anything regarding tooltip transparency elsewhere either, maybe I missed it.