Very cool, but I totally don't understand the UI. :-) * I was able to edit some text at some point, but I don't know how I did it, and I don't know how to do

Very cool, but I totally don't understand the UI. :-) * I was able to edit some text at some point, but I don't know how I did it, and I don't know how to do it again. Can the text of all elements be edited? * Double clicking an element deletes it?