Updating gWidgets elements in R - r

Question

I'm having trouble updating graphical elements in R and I can't figure it out. I'd appreciate a little push.
I'm trying to make a simple GUI which is prepopulated with some options, but when a button is pressed the database is queried (the query is modified by the GUI), and the result needs to change what's available in the gcomboboxes and gtables. I'm frankly amazed at how simple it is to create such an excellent environment in R.
I don't believe I can modify the body of gcomboboxes or gtables once they're on screen (if I can, that's probably my preferred solution). I also don't believe I can destroy individual elements of a glayout, only the entire glayout. But how do I get it back in the right order?
# Small example for GUI element creation and destruction
if(!require("RGtk2")) {library("RGtk2")}
if(!require("digest")) {library("digest")}
if(!require("cairoDevice")) {library("cairoDevice")}
if(!require("gWidgets")) {library("gWidgets")}
if(!require("gWidgetsRGtk2")) {library("gWidgetsRGtk2")}
nw<-gwindow("Test",toolkit=guiToolkit("RGtk2"))
g<-ggroup(horizontal=FALSE,cont=nw)
t1<-glayout(container=g) # Header
t2<-glayout(container=g) # Dynamic middle
t3<-glayout(container=g) # Footer
t1[1,1]<-gcombobox(c("foo","bar"))
t1[1,2]<-gbutton("Update")
t2[1,1]<-gframe("",container=t2)
t2[2,1]<-gcombobox(c("violin","metal"))
t2[3,1]<-gtable(c("YoYoMa","Metallica"))
t3[1,1]<-glabel("Filler text",container=t3)
delete(g,t2) # Unable to delete t2[2,1] and t2[3,1]
t2<-glayout(container=g)
#t2[2,1]<-gcombobox(c("violin","metal","pop")) ### Nope...
#t2[3,1]<-gtable(c("YoYoMa","Metallica","UB40"))
#add(t2,gcombobox(c("violin","metal","pop"))) ### Nope...
#add(t2,gtable(c("YoYoMa","Metallica","UB40")))
All my added elements go below my footer text. How do I straighten it out so they go between the header and footer?
If I don't delete the glayout, it looks like I can modify the contents of the gcombobox, but the UI doesn't really reflect it. I can see new text when I click the arrow, but the selection no longer appears to change.
...
t2[2,1]<-gcombobox(c("text to remove","violin","metal"))
t2[3,1]<-gtable(c("YoYoMa","Metallica"))
t3[1,1]<-glabel("Filler text",container=t3)
t2[2,1]<-gcombobox(c("violin","metal","pop")) # "text to remove" remains selected regardless of user input
t2[3,1]<-gtable(c("YoYoMa","Metallica","UB40"))
It was a little frustrating, but this is working well for me. I'll leave this solution here in case anybody else has trouble.
# Small example for GUI element creation and destruction
if(!require("RGtk2")) {library("RGtk2")}
if(!require("digest")) {library("digest")}
if(!require("cairoDevice")) {library("cairoDevice")}
if(!require("gWidgets")) {library("gWidgets")}
if(!require("gWidgetsRGtk2")) {library("gWidgetsRGtk2")}
nw<-gwindow("Test",toolkit=guiToolkit("RGtk2"))
g<-ggroup(horizontal=FALSE,cont=nw)
t1<-glayout(container=g) # Header
t2<-glayout(container=g) # Dynamic middle
t3<-glayout(container=g) # Footer
t1[1,1]<-gcombobox(c("foo","bar"))
t1[1,2]<-gbutton("Update")
t2[1,1]<-gframe("",container=t2)
t2[2,1]<-gcombobox(c("text to remove","violin","metal"))
t2[3,1]<-gtable(c("YoYoMa","Metallica"))
t2[3,1]<-gtable(BandList)
t3[1,1]<-glabel("Filler text",container=t3)
t2[2,1][]<-c("violin","metal","pop")
svalue(t2[2,1])<-"pop" #otherwise it's confused about defaults
t2[3,1][]<-c("YoYoMa","Metallica","UB40")

Answer 1

I found a way to edit the contents already on screen without needing to delete the screen elements.
# Small example for GUI element creation and destruction
if(!require("RGtk2")) {library("RGtk2")}
if(!require("digest")) {library("digest")}
if(!require("cairoDevice")) {library("cairoDevice")}
if(!require("gWidgets")) {library("gWidgets")}
if(!require("gWidgetsRGtk2")) {library("gWidgetsRGtk2")}
nw<-gwindow("Test",toolkit=guiToolkit("RGtk2"))
g<-ggroup(horizontal=FALSE,cont=nw)
t1<-glayout(container=g) # Header
t2<-glayout(container=g) # Dynamic middle
t3<-glayout(container=g) # Footer
t1[1,1]<-gcombobox(c("foo","bar"))
t1[1,2]<-gbutton("Update")
t2[1,1]<-gframe("",container=t2)
t2[2,1]<-gcombobox(c("text to remove","violin","metal"))
t2[3,1]<-gtable(c("YoYoMa","Metallica"))
t2[3,1]<-gtable(BandList)
t3[1,1]<-glabel("Filler text",container=t3)
t2[2,1][]<-c("violin","metal","pop")
svalue(t2[2,1])<-"pop" #otherwise it's confused about defaults
t2[3,1][]<-c("YoYoMa","Metallica","UB40")