The feature should force the user to assign an ID (like the Text Input has a name) to any image component created.
The GUI procedure block should accept as a parameter an image component's ID and also a dropdown with all the texture assets.
The use case is to make the UI more reusable. For example: right now If I have several UIs that share the same text fields (NBT tag loaders) but the images change, I need to create a new UI element, but being able to change the texture of an image component makes easier to apply a template pattern.
Changing image is not possible by design of GUI components, but it can be conditionally shown. This said feature is in my internal todo planned.
[#65599] Custom GUI labels and images can now be conditionally shown using conditions system
Thanks Klemen, that should do the trick too!