Can I construct a complex dialogue dynamically through code? If not, it's worthless, because static dialogues are quite easy to implement without a GUI system just by drawing some sprites and looking to see where the mouse clicks go.
Hmm, so dynamically creating dialogue boxes, do you mean you store a large set of possible text responses and the dialogue GUI can dynamically resize itsellf based on the amount of text? Let's say the dialogue had anywhere from 0-5 clickable response lines and those spawned different dialogues, maybe ultimately leading to a dialogue with a reward in it (completed a quest for example). This shouldn't be too difficult to do as long as a flexible dialogue prefab is constructed and then you call it's creation with the parameters you want in your game code. I haven't gotten far enough in my own game to do this yet (create a dynamic dialogue system), but I will definitely make sure I consider all the possible use cases.
Can it layout objects for me in lists and grids? If not, it's going to be a nightmare to use for any complex data. I need to be able to push an arbitrary number of objects into a container and have it position them for me - otherwise, I may as well just render them directly myself.
Yea this definitely be doable with a panel GUI object. My editor started out as a world map generator, so it can randomly generate say 1,000 connected solar systems with the ability to highlight a path between any 2 given systems using a BFS algorithm using the GUI hierarchy, each with randomly generated tooltips, names, hoverstate animations, etc all within a pannable, zoomable parent panel. The way entities are related to eachother spatially within a panel parent should be highly configurable out of the box. So to create a grid like inventory system GUI for example, the children entities would have a 90 degree step and 0 degree random variation.
Can it handle scrolling areas? This is the main thing that stops me writing my own GUI in Unity - since there is no access to scissor rectangles I can't implement scrolling areas myself. NGUI have got around this with custom shaders, which is a fun hack, but they obviously have no clue how to handle input management properly so that's a non-starter.
So, a scrollable panel parent should either be able to dynamically resize itself or force a dynamic rescaling of the children objects to fit a fixed parent size. The input system is all based on one ray cast to determine where your mouse is currently located and which actions are available depend on the GUI prefab your on. I'm pretty surprised this requires custom shaders in NGUI. Are the items you want to fit within a scrollable parent all different sizes or something?
Can I change the state of the GUI easily? HTML has this 100% right - if you want to change something, it's one simple function call to find it, then one property access to change it. No need to hook up signals and slots. No need to manually traverse the tree of elements. No need to pre-create the element so that you can hold a reference to it and change it later.
Basically I currently have it as GameObject.Find to get an arbitrary reference, the editor forces a naming convention such that the any given can be constructed using prefixes of the parent objects, to ensure that an arbitrary hierarchy object has a unique name. Problem is the names can get pretty long, I might need to rethink this design later. Once you have a reference to it, you can cast it to the type of GUI object it is to access the data. Additionally, you will also be able to add, delete, get, or set arbitrary data for any GUI object.
Can the GUI effectively tell me when things happen? Usually this is done with callbacks attached to events on controls. Some GUIs like to run in immediate mode which makes life much harder since in most languages you only get one return value from a function, meaning each control can only really signal one type of event.
This should be easy enough :)
Thanks for the ideas, this is a pretty complex, but fun project :)