Like others have said, essentially in your game loop you'll need to:
1. Set the render window's view to your "main" view.
2. Draw all the "game" stuff. The moving parts, etc.
3. Set the render window to a separate "UI" view.
4. Draw the UI stuff.
The UI's positions can be anything at all. Since you're drawing them at a completely separate time as the game entities, and because it's on a completely different view, doing stuff like moving the "main" view won't effect the UI stuff at all.