The Gio project started out as a simple cross-platform Go library for creating user interfaces for mobile and desktop devices. However, it soon became apparent that the immediate mode programming model was a key factor in its long-term adoption. Immediate mode programming offers a stateless approach to UI development, which is different from the traditional retained mode model used by most GUI toolkits. The article provides examples comparing Gio’s immediate mode approach to the retained mode approach in popular toolkits. It highlights the advantages of immediate mode in terms of control over event handling, drawing, layout, and user input.
https://eliasnaur.com/blog/immediate-mode-gui-programming