It's not a bug, it's the way the new UI is designed. Enable the "Stretch UI" setting if you want UI forced to 4:3 mode. It will look stretched but elements will be in right place. The old UI was god awful and while it was better suited for 4:3 resolutions, it didn't look right in 1920x1080. 99% of users today use 16:9 monitors because that's what the market pushes for, there are even some big games released recently that don't work at all in non-16:9 resolutions.
Well it's a bug because it affects not only the UI - did you read it affects the fps counter, plugins overlays and virtual mirrors placement either? Those elements shouldn't be connected with simple UI elements.
