Shoutbox

I'd like to see a "Properties" and "Events" pane for windows and controls! Like Visual Studio for C#/VB(.Net) forms/controls. You can select a control (or the window itself) and modify its properties, and create event handlers for it. Of course, for properties that are not strings: we have a drop-down menu for multiple choices (True/False, reference to other elements, ...), number-only textfield for numbers, color picker for colors, etc!
I actually think the data structure (or how it should be called) is not hard to create as long as we have the source file of the schema.

As for pixel-precise window rendering - I believe it's gonna be a lot of nasty work without Yuna releasing Plus!'s window rendering codes.