I'm intending to create an application displaying freely scrollable and editable, dynamic mind-map like structures and layouts, that should equally work and show on Windows, Mac, Android and iOS. Coming from game development, I considered using Unity3D which does a good job in having equal looks on every platform, but unfortunately is bad in layouting and especially in using text. (plus the whole 3D overhead..)
I also have some experience in Xamarin, but from what I know so far it appears to be not very flexible in creating more complex GUIs. Also, Xamarin seems to require UIs to be programmed for each platform individually.
Is there any framework or library made for creating non-conventional, flexible graphical user interfaces, that look the same on every platform?
I considered using MonoGame for Xamarin to perhaps get the best from both worlds (games & conventional app development), but perhaps there are better options for creating visually rich apps?