Procedural Images Within GUIs and Overlays

It is a painstaking process creating several textures, components, and procedures when making GUIs and overlays.

There should be a feature within the GUI/Overlay editors that allows procedural images.

For example, a component that shows an image in an overlay depending on what biome the player is in. 
There would be an image component with a new image-type return procedure set as the value.
The "return" block can accept plain textures as input, or a block that grabs a texture with text input.