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## Loading the New Classes

Usually, you can use a separate script file to store the implementaion of each new widget class. If you have several of those files, it will be a good idea to group the files into a single directory and create a `tclIndex` file for them so that the new classes can be auto-loaded.

Suppose you have put the class files into the directory `/usr/my/tix/classes`. You can create the `tclIndex` file using the `tools/tixindex` program that comes with Tix:

> `cd /usr/my/tix/classes
> /usr/my/Tix8.1/tools/tixindex *.tcl`

The `tclIndex` file must be created by the `tixindex` program. You cannot use the standard `auto_mkindex` command that comes with Tcl.

Once you have created the `tclIndex` file, you can use your new widget classes by auto-loading. Here is a small demo program that uses the new TixArrowButton class:

> `#!/usr/local/bin/tixwish
> lappend auto_path /usr/my/tix/classes
> # Now I can use my TixArrowButton class!
> #
> tixArrowButton .arr -direction n
> pack .arr`