I use ace config dialog. It makes doing GUI options easy, but the limitations drive me nuts at time.
In my addon I collect a list of debuff and buffs, and I want to list them out and be able to click them or mouse over them with a tooltip.
aceconfig has no feature where you can list stuff like that. So I had to use the description type it looks good, but you cant click a hyperlink on it.
Don't think you can do a custom control since that only supports editbox or dropdowns.
Maybe ace3 on day can get some kind of read only output box. Like for the help file in my addon I use a big editbox, since you can cut text out from it. Was a good way to do it, but not how I would like to do it.
A custom control can be anything you want. You could make a Bonzi Buddy in AceGUI. Even if you have to tell AceConfig it's an editbox, that doesn't really matter, since it will just go back to AceGUI and say "make an editbox using the BonziBuddy custom control" and then your custom control does whatever it wants, even if that something isn't actually an editbox. Just make sure your control has all the right methods to let AceGUI/AceConfig go on thinking it's an editbox, eg. SetText.