[R] Why can't I make use of tcltk in this installation?

[Patrick Connolly]

> sessionInfo()
R version 3.5.0 (2018-04-23)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.5 LTS

Matrix products: default
BLAS: /home/pat/local/R-3.5.0/lib/libRblas.so
LAPACK: /home/pat/local/R-3.5.0/lib/libRlapack.so

locale:
 [1] LC_CTYPE=en_NZ.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_NZ.UTF-8        LC_COLLATE=en_NZ.UTF-8    
 [5] LC_MONETARY=en_NZ.UTF-8    LC_MESSAGES=en_NZ.UTF-8   
 [7] LC_PAPER=en_NZ.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_NZ.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] utils     stats     grDevices graphics  methods   base     

other attached packages:
[1] lattice_0.20-35

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.17     dplyr_0.7.6      assertthat_0.2.0 grid_3.5.0      
 [5] R6_2.2.2         magrittr_1.5     pillar_1.2.3     rlang_0.2.1     
 [9] bindrcpp_0.2.2   tools_3.5.0      glue_1.2.0       purrr_0.2.5     
[13] compiler_3.5.0   pkgconfig_2.0.1  bindr_0.1.1      tidyselect_0.2.4
[17] tibble_1.4.2    
> capabilities()
       jpeg         png        tiff       tcltk         X11        aqua 
       TRUE        TRUE        TRUE       FALSE        TRUE       FALSE 
   http/ftp     sockets      libxml        fifo      cledit       iconv 
       TRUE        TRUE        TRUE        TRUE       FALSE        TRUE 
        NLS     profmem       cairo         ICU long.double     libcurl 
       TRUE       FALSE        TRUE        TRUE        TRUE        TRUE 
> 

If I try to load tcltk, no surprise...

> require(tcltk)
Loading required package: tcltk
Error: package or namespace load failed for ‘tcltk’:
 .onLoad failed in loadNamespace() for 'tcltk', details:
  call: fun(libname, pkgname)
  error: Tcl/Tk support is not available on this system
Warning message:
S3 methods ‘as.character.tclObj’, ‘as.character.tclVar’, ‘as.double.tclObj’, ‘as.integer.tclObj’, ‘as.logical.tclObj’, ‘as.raw.tclObj’, ‘print.tclObj’, ‘[[.tclArray’, ‘[[<-.tclArray’, ‘$.tclArray’, ‘$<-.tclArray’, ‘names.tclArray’, ‘names<-.tclArray’, ‘length.tclArray’, ‘length<-.tclArray’, ‘tclObj.tclVar’, ‘tclObj<-.tclVar’, ‘tclvalue.default’, ‘tclvalue.tclObj’, ‘tclvalue.tclVar’, ‘tclvalue<-.default’, ‘tclvalue<-.tclVar’, ‘close.tkProgressBar’ were declared in NAMESPACE but not found 
> 

The question is:  What do I have to do to get Tcl/Tk support?
>From the bash prompt:
 > aptitude search tcltk
p   hfsutils-tcltk             - Tcl/Tk interfaces for reading and writing Macintosh volumes 
p   hfsutils-tcltk:i386        - Tcl/Tk interfaces for reading and writing Macintosh volumes 
p   libtcltk-ruby              - Tcl/Tk interface for Ruby           
p   libtcltk-ruby1.9.1         - Tcl/Tk interface for Ruby 1.9.1
p   libtcltk-ruby1.9.1:i386    - Tcl/Tk interface for Ruby 1.9.1
p   r-cran-tcltk2              - GNU R package for Tcl/Tk additions 
p   ruby2.0-tcltk              - Ruby/Tk for Ruby 2.0
p   ruby2.0-tcltk:i386         - Ruby/Tk for Ruby 2.0  

That's the same as what I get on another computer on which tcktl is
available, so it didn't surprise me when installing the r-cran-tcktl
package didn't help.

Where else should I be looking for a difference?

TIA


-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
 {~._.~}                   Great minds discuss ideas    
 _( Y )_  	         Average minds discuss events 
(:_~*~_:)                  Small minds discuss people  
 (_)-(_)  	                      ..... Eleanor Roosevelt
	  
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.