[R-gui] Tcl/Tk examples update

[James Wettenhall]

Hi,

Last year I put some examples of creating Tk widgets 
in R (using Peter Dalgaard's tcltk package) on a webpage:
http://bioinf.wehi.edu.au/~wettenhall/RTclTkExamples/

Since R 1.8.0, it has become possible to interact with the Tktable 
widget extension in a new way (through the new tclArray 
interface in tcltk), and it has become easier to create Tcl lists 
from R vectors (useful in combo-boxes).  So I have finally 
cleaned up the some of the messy code on that webpage, particularly
http://bioinf.wehi.edu.au/~wettenhall/RTclTkExamples/tktable.html
and
http://bioinf.wehi.edu.au/~wettenhall/RTclTkExamples/DropDown.html

Creating a (drop-down) combo box from an R vector is now easy if 
you have the BWidget extension:
Rvector <- c("one","two","three")
tt <- tktoplevel()
tclRequire("BWidget")
comboBox <- tkwidget(tt,"ComboBox",values=Rvector)
tkpack(comboBox)

Also I removed a few instances of .Tcl(paste(...)) which is more 
prone to "quoting hell" problems than tkcmd(...) and tkwidget(...) 
and possibly slower too.

Sorry to people on this list who are already R-Tcl/Tk experts or 
who aren't interested.  

Feel free to point out errors etc.

Regards,
James