expose an API for creating UI elements

[havok2063]

Is it possible to expose an API to create more complex custom UI elements? For example, I'd to create a button with a context menu, similar to the current Settings or Overlays button, with my own content. I'd also like to re-use some of your existing elements, like the color picker, or visibility, and remove buttons.

What is the best way to create more complex custom UI elements?

Or alternatively, is there an easy way to modify Aladin's existing elements? For example, adding a color picker option to a new Catalog layer, under the Overlays menu, to interactively change the source color?