Support SVGs in UI
SVG or similar non-raster formats is critical in designing new UI elements that scale well across different viewports. It also allows for you to easily create dynamic elements. It is necessary in any UI rendering library, OpenMW included.
OSG has have a reader/writer plugin for an SVG, but it looks like it transforms the SVG into a raster image, which defeats the entire point of an SVG when you're using it to render UI.