Getting width of Tk text widget via tcltk

Dear Peter,

As you can see from the expression, I didn't use integer division, nor did I
round() or floor(). Here's my original example, using a monospaced font:

library(tcltk)
top <- tktoplevel()
textWindow <- tktext(top, bg="white", height=20, width=80, wrap="none",

+     font=tkfont.create(family="courier", size=10))

tkgrid(textWindow, sticky="news")

<Tcl>  

tkgrid.rowconfigure(top, 0, weight=1)

<Tcl>  

tkgrid.columnconfigure(top, 0, weight=1)

<Tcl>  

tkcget(textWindow, width=NULL)

<Tcl> 80 

tkwinfo("width", textWindow$ID)

<Tcl> 646 

(as.numeric(tkwinfo("width", textWindow$ID))

+      - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 4) /
+      as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 79.75

(as.numeric(tkwinfo("width", textWindow$ID))

+      - 2*as.numeric(tkcget(textWindow, borderwidth=NULL)) - 2) /
+      as.numeric(tkfont.measure(tkcget(textWindow, font=NULL), "0"))
[1] 80

I believe that the right answer is 80, and this appears correct visually,
confirmed by typing in the window.

tkwinfo("width", textWindow)

(as.numeric(tkwinfo("width", textWindow))

(as.numeric(tkwinfo("width", textWindow))