(1) Run help.start() in R to get HTML help, then click on Packages,
then click on tcltk.
(2) Read the ActiveTcl help and learn how to convert Tcl options to R arguments, e.g.
-background white
becomes
background="white",
(3) Read Peter Dalgaard's articles in Rnews : Rnews 2001, Vol. 3 and Rnews 2002, Vol. 3.
(4) Study the demos in the R tcltk package, e.g. tkdensity and
tkttest.
(5) Study the tkWidgets and widgetTools packages at Bioconductor.
(6) Read and participate in R-Help and R-SIG-GUI.
(7) Search the web for TclTk examples, and don't ignore them completely if they use a language other than R, e.g. Perl or Python. A lot can be learned from these examples, e.g. Python-Tk Events and Bindings.