Suggestion: Add callback function to Gui#update method

[cameronbrown5]

Hi there, I'm currently working on a gui and I'd like to add navigation buttons that will appear only if there's a page to go to. Right now, I have to have click functions on the items that will either add or remove the item depending on which page you're on. If we could have a callback function that is called when the gui is updated, it would simplify this to adding or removing buttons whenever I update the panel for the new page. This also would add a ton of opportunity for things like animations while in guis.

I'm willing to fork and create a pull request for this if you'd like.

[stefvanschie]

To my understanding you would like to have some kind of Gui#setOnUpdate(Runnable) method for which the provided Runnable is ran every time the gui is updated. Then you'd change the navigation in that Runnable.
I personally don't see the utility in such a method for your purposes. Currently you'd update the navigation whenever the page is swapped, generally whenever the player clicks a navigation button. With your proposed solution, you'd have the same kind of code, but now in a different place. I personally don't think that makes enough of a difference to warrant this addition.
Also, in my opinion it's easier to make the items/panes for the navigation invisible if you can't go in that direction. This probably already helps make your code easier.