I've now updated the completion popups used in the advanced editor plugin to get a better display of the available information

For completion items that are related to functions with a help page, we now get this popup

When completing arguments of functions, the text of the argument is grabbed from the help page (if available), and displayed as such:

For functions that do not have help page, such as functions in the global environment, a deparse of the function is displayed

It is probably better to build the plugin from source, but otherwise I have posted a build here

I am currently working on ways to bring this completion mechanism to the console as well