Does an interactive transliteration interface like this seem useful to you?

Here’s something I have been working on:

I’ve often found myself wanting to transcribe something in an unfamiliar orthography (for comparative purposes, or whatever), and I don’t want to go through all the trouble of installing and learning a specialized keyboard. I just want some way to get the dang text into the computer. The idea behind this little interface is that you can edit transliteration rules “as you go”, looking up unusual characters via aliases like acute or schwa or whatever. (Those aliases should be editable more easily too, come to think of it…)

I find myself opening up this little doohickey on fairly regular occasions, and I’m wondering if anyone would like to try it.