Multiline Comment Workarounds?

A sort of block comment uses an if statement:

if(FALSE) {
  all your code
}

It works, but I almost always use the block comment options of my editors (RStudio, Kate, Kwrite).

A neat trick for RStudio I've just discovered is to use #' as this creates an self-expanding comment section (when you return to new line from such a line or insert new lines into such a section it is automatically comment).

[Update] Based on comments.

# An empty function for Comments
Comment <- function(`@Comments`) {invisible()}

#### Comments ####
Comment( `

  # Put anything in here except back-ticks.

  api_idea <- function() {
    return TRUE
  }

  # Just to show api_idea isn't really there...
  print( api_idea )

`)
####

#### Code. ####
foo <- function() {
  print( "The above did not evaluate!")
}
foo()

[Original Answer]

Here's another way... check out the pic at the bottom. Cut and paste the code block into RStudio.

Multiline comments that make using an IDE more effective are a "Good Thing", most IDEs or simple editors don't have highlighting of text within simple commented -out blocks; though some authors have taken the time to ensure parsing within here-strings. With R we don't have multi-line comments or here-strings either, but using invisible expressions in RStudio gives all that goodness.

As long as there aren't any backticks in the section desired to be used for a multiline comments, here-strings, or non-executed comment blocks then this might be something worth-while.

#### Intro Notes & Comments ####
invisible( expression( `
{ <= put the brace here to reset the auto indenting...

  Base <- function()
  {      <^~~~~~~~~~~~~~~~ Use the function as a header and nesting marker for the comments
         that show up in the jump-menu.
         --->8---
  }

  External <- function()
  {
    If we used a function similar to:
      api_idea <- function() {

        some_api_example <- function( nested ) {
          stopifnot( some required check here )
        }

        print("Cut and paste this into RStudio to see the code-chunk quick-jump structure.")
        return converted object
      }

    #### Code. ####
    ^~~~~~~~~~~~~~~~~~~~~~~~~~ <= Notice that this comment section isnt in the jump menu!
                                  Putting an