Sorry, I don't know of an existing one, but if you use BigStringEditor and UITypeEditor for the "?"s, and define a class BigStringEditor as in the included code (sorry, I don't have VB.Net on my machine, but the code should be almost the same) then when you click in the property a "..." will appear (I think you need to set Browsable(true) also) and if you click on that a 100x100 dialog will appear which will let you edit.