[R-gui] MainFrame Tk BWidget

[James Wettenhall]

Enrique,

Have a look at the BWidget demos that come with ActiveTcl.  

For your amusement, here are my efforts to totally confuse 
myself about the MainFrame widget.  Does it require "." as a 
parent?  What difference does having a menu make?
Three cases below.
(1) A MainFrame widget with no menu and with parent tt
(2) A MainFrame widget with a menu and with parent tt
(3) A MainFrame widget with a menu and with parent .

(1) A MainFrame widget with no menu and with parent tt
library(tcltk)
tt <- tktoplevel()
tclRequire("BWidget")
mainFrame <- tkwidget(tt,"MainFrame")
tkdestroy(mainFrame) # Optional
tkdestroy(tt)
# Notes:  No problems with Case (1).  :)


(2) A MainFrame widget with a menu and with parent tt
library(tcltk)
tt <- tktoplevel()
tclRequire("BWidget")
exit <- function()
{
  tkdestroy(mainFrame)
  tkdestroy(tt)
}
mainMenu <- 
  paste("\"&File\" all file 0 ",
  "{{command \"E&xit\" {} \"Exit Case 2\" {}",
  "-command \"",.Tcl.callback(exit),"\"}}")
mainFrame <- tkwidget(tt,"MainFrame",menu=mainMenu)
tkpack(mainFrame)         

# Notes:  Now I can crash my R session by typing 
# either of tkdestroy(tt) or tkdestroy(mainFrame)
# or clicking "Exit" in the File menu.
# The following DOESN'T crash my R session and 
# appears to destroy the menu (and frame?):

tkcmd("MainFrame::_destroy",mainFrame)

# But then tkdestroy(tt) still crashes my R session.
# Now if instead of tkdestroy(tt), I click on the 
# close button at the top-right-hand corner of tt, 
# (after doing MainFrame::_destroy), I get this:

Application Error
Error: can't read "_widget(.1.1,top)": no such element in array
can't read "_widget(.1.1,top)": no such element in array
can't read "_widget(.1.1,top)": no such element in array
    while executing
"$_widget($path,top) configure -menu {}"
    (procedure "MainFrame::_destroy" line 6)
    invoked from within
"MainFrame::_destroy .1.1"
    (command bound to event)

# Note that the menu option of BWidget::MainFrame is described 
# as "read-only".  Is that a clue?



(3) A MainFrame widget with a menu and with parent .
library(tcltk)
tkwm.deiconify(".")
tclRequire("BWidget")
exit <- function()
{
  tkcmd("MainFrame::_destroy",mainFrame)
  tkwm.withdraw(".")
}
mainMenu <- 
  paste("\"&File\" all file 0 ",
  "{{command \"E&xit\" {} \"Exit Case 3\" {}",
  "-command \"",.Tcl.callback(exit),"\"}}")
mainFrame <- tkwidget(.TkRoot,"MainFrame",menu=mainMenu)
tkpack(mainFrame)         

# Notes: Using the Tk root window "." is ugly
# because if you destroy it then I think you have to 
# restart R or at least reload the tcltk package.  The 
# exit function used here simply hides the "."
# window.  It doesn't really destroy anything.


Well, maybe that will give others some clues in order to 
go further...

Regards,
James