[Rd] Several libraries won't load with (PR#6927)

[Liaw, Andy]

> From: Uwe Ligges
> 
> rmh at temple.edu wrote:
[...]
> > 3. Martin's comment
> >    > Are you running another version of R simultaneously? 
> >    > IIRC, Windoze has the nice feature to sometimes lock 
> files when 
> >    > it shouldn't.   
> > isn't the problem.  I have two Rgui and one iESS [R] 
> running and all three
> > have loaded the Hmisc and multcomp packages.
> 
> Maybe, but after you have loaded the package, you cannot 
> overwrite it, 
> because the dll files are locked (yes, dlls are locked when 
> in use under 
> Windows). So Martin's analysis was correct.
> Therefore you have to detach those packages you want to re-install or 
> update (and also close all chm documentation - or even better close 
> corresponding instances of R).
> 
> Uwe
> 
> > Rich

In `older' versions of R on Windows, detach()ing a package that contains dll
does not unload (or at least unlock) the dll.  I have not tried the current
version.  It's much safer to quit _all_ instances of R, restart, and
re-install the packages.  Pre-compiled packages for Windows can be installed
in sort of four ways:

1. The Rgui menu
2. install.packages() from the R prompt
3. Download the zip file and unpack in the desired directory
4. Download the zip file and use install.packages(..., CRAN=NULL)

For #3 above, link.html.help() should be run at the R prompt post-unzip.

HTH,
Andy