Mastering Perl/Tk

Chapter 7. The Listbox Widget

A Listbox widget is designed to list strings of text, one text string per line. You can then select a line or multiple lines from the Listbox on which to perform other operations. Some examples of things to place inside a Listbox include:

• An alphabetized list of cities.

• A list of servers to log in to. Select a server name and then enter a name and password into some Entry widgets. Click the OK Button to log in.

• A list of operating systems.

• A list of payment options: MasterCard, American Express, Visa, Check, Cash.

Figure 7-1 shows an example of a Listbox.

Figure 7-1. Listbox widget

A Listbox is ideal for replacing Radiobuttons or Checkbuttons that have become too numerous to display on the screen. Usually 3 or 4 Checkbuttons or Radiobuttons aren’t a big deal, but if you try to display 10 at a time, the window could get a little crowded. A group of Radiobuttons can be replaced by a Listbox that limits the number of selections to one and has a default selection. A bunch of Checkbuttons can be replaced by a Listbox that allows multiple selections.

There are times when you’d like several Listboxes arranged side-by-side that scroll in parallel. While the standard Perl/Tk distribution doesn’t have such a widget, Chapter 23 highlights some user-contributed “multi-Listbox” widgets.

An alternative to the plain Listbox are the HList and TextList widgets, which ...