(tested under FF 3.6)
I want to edit an empty string property : I try to double clic but... I don't know where exactly to clic and even if I try pixel by pixel : I just can't

I think more over the double clic, a pen should be available in front of every property

updated June 22 :
Now the pen is available, and the TextField appears. But after validating, an error happens. It seems that using the function javax.jcr.Node.setProperty(String name, String value, int type) in SetPropertyAction.java cause this bug.