How can I show the actual variable values in the RequestPane>QueryURL>SingleLineEditor instead of the variables' keys?

[developingharry]

I'm guessing I can overwrite the url using a pre-request script but I think it'd be nifty if I could change the url as each new path param was entered, or if the env in question held a matching value.
Like this - the colour retained to highlight that it's...dynamic for want of a better word.