R help - Apr 2009 - disappearing dialog boxes when using tcltk

Dear all,

I'm trying to use tcltk to build a small
user-interface and couter the problem:

It seems that sometimes the dialog box will be
minimized automatically though I want it to be on top
of the screen all the time. 

For example, when runing the following code, if you
type in "a1", "a2", "a3", etc when being asked for
an
integer, the program is supposed to keeping asking you
until you give an integer. The program runs fine, but
the dialog box is not always on top, and it is
annoying having to maximized it every time (the wierd
thing is that sometimes it is Ok, sometimes it is not.
So I don't know the problem.)

Millions of thanks!

Hua

##==============================================## Add Dialog Box (with only
"OK" button)
##==============================================modalDialogOK <-
function(title,question,entryInit,entryWidth=10)
{
  returnValOnCancel="ID_CANCEL"
  dlg <- tktoplevel()
  tkwm.deiconify(dlg)
  tkgrab.set(dlg)
  tkfocus(dlg)
  tkwm.title(dlg,title)
  textEntryVarTcl <- tclVar(paste(entryInit))
  textEntryWidget <-
tkentry(dlg,width=paste(entryWidth),textvariable=textEntryVarTcl)
  tkgrid(tklabel(dlg,text="       "))
  tkgrid(tklabel(dlg,text=question),textEntryWidget)
  tkgrid(tklabel(dlg,text="       "))
  ReturnVal <- returnValOnCancel
  onOK <- function()
  {
    ReturnVal <<- tclvalue(textEntryVarTcl)
    tkgrab.release(dlg)
    tkdestroy(dlg)
    # tkfocus(dlg)
    tkfocus(ttMain)
  }
  OK.but     <-tkbutton(dlg,text="   OK  
",command=onOK)
  tkgrid(OK.but)
  tkgrid(tklabel(dlg,text="    "))

  tkfocus(dlg)
  tkbind(dlg, "<Destroy>", function()
{tkgrab.release(dlg);tkfocus(ttMain)})
  tkbind(textEntryWidget, "<Return>", onOK)
  tkwait.window(dlg)

  return(ReturnVal)

}



##==============================================## main function
##==============================================require(tcltk)
ttMain <- tktoplevel()
tkwm.title(ttMain,"Number")
tkdestroy(ttMain)


#initial values are set
numAll = ""
speAll = NULL
yrunit = ""

ttMain <- tktoplevel()
tkfocus(ttMain)
numAll <- as.numeric(modalDialogOK("Number","Put in an
integer greater than 1:",entryInit=numAll))
tkdestroy(ttMain)
    
while (is.na(numAll) || numAll==0 || numAll==1) {
        ttMain <- tktoplevel()
        tkfocus(ttMain)
        ReturnVal <-
tkmessageBox(title="Number",message="Error! The number
of should be NUMERICAL and be greater than
1!",icon="info",type="ok")
        tkdestroy(ttMain)

        ttMain <- tktoplevel()
        tkfocus(ttMain)
        numAll <-
as.numeric(modalDialogOK("Number","Put in an integer
greater than 1:",entryInit=numAll))
        tkdestroy(ttMain)

}


##==============================================## end of code
##===============================================