Widgets and User Interaction

Widgets are arranged in a hierarchy, using pathnames separated by periods:

    .
        .menubar
            .menubar.file
                .menubar.file.load
                .menubar.file.print
                .menubar.file.quit
            .menubar.help
                .menubar.help.about
                .menubar.help.tutorial
        .frame
            .frame.canvas
            .frame.scrollbar

Geometry managers arrange widgets on the display.

• pack autosizes and arranges widgets in rows and columns.
• place puts widgets at specific coordinates relative to their parent widget.

User interaction is based on callbacks.

• Widgets can execute other Tcl commands when invoked.
• A generic event/callback binding mechanism is also provided:
  bind .frame.canvas <Expose> {incr n; redraw}

A wish is a standard windowing shell which accepts Tcl/Tk scripts.