# Customizing the menus in affylmGUI (for Advanced users)

The pull-down menus in affylmGUI are defined in `affylmGUI-menus.txt` in the `etc` subdirectory of the `affylmGUI` package installation. To find out exactly where this directory is on your computer, you can paste the following into R:

    system.file("etc",package="affylmGUI")

R source files can be added to this `etc` directory (and must have extension `.R`).

Try uncommenting (i.e. removing the # from) the histogram menu item in `affylmGUI-menus.txt` to enable the histogram command in the plot menu.

You can add as many menu items as you wish.

The reason that the histogram example plots the graph in the standard R graphics device rather than in a Tk window is simply to keep this example brief and avoid calling `tkrplot`. Generally graphs are plotted in Tk windows and users of the Windows operating system can keep their main RGui window minimized while they run `affylmGUI`.