A WDialog with Fade animation and Bootstrap 3 theme displays a black dialog cover.
With github Wt 3.3.6-6-gbadb151, dismissing a Bootstrap3-themed WDialog or WMessageBox with Fade animation displays a solid black dialog cover rather than the translucent cover provided when animation is not employed.
The attached test program (same as attached to #5265) can be used to demonstrate the issue. Since Wt provides the ability to have user-provided dialog covers, this is an easy issue to workaround. Ideally, though, Wt should default to display the same translucent cover with Fade animation as without animation.