Turns out I needed to add "exportselection=0". So: foo.lb <- tklistbox(root, height = 5, selectmode = "extended", exportselection = 0) Got this from: http://tolstoy.newcastle.edu.au/R/e2/help/06/12/6955.html (That's what I get for assuming there'd be no tcl/tk questions on this list. D'oh!) Cheers! Mark -- I'm taking reality in small doses to build immunity.