Instructions For Writing Tclets

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These instructions should be updated shortly for the new version 2.0 features

Here is a cookbook for how to write your first tclet:

That's IT. You're done. This page should look like what you've created above.

Feedback is appreciated! If you want to send in a comment, just email to All comments are welcome, and email will be acknowledged if you include a reply-to address.

Safe Tcl and Safe Tk

You can test your Tclet by running it in the wish shell; you don't have to run it inside Netscape. However, when you are running in the Tcl plugin you have a restricted set of Tcl commands for security reasons. The following Tcl commands are not available:

Stand Alone or Plug In?

You can detect if you are running in the plugin by testing for the existing of the embed_args variable. This is an array whose values come from the <embed> tag in the document. For example, $embed_args(src) contains the name of the Tcl script for the applet. You can put whatever NAME=VALUE pairs you want in the <embed> tag. The Plugin looks at SRC, WIDTH, and HEIGHT. Any others are for your own use.

Other Tcl variables defined especially for the plugin are:

String describing the plugin version such as "1.0"
String describing the plugin patch level, such as "1.0"

Window sizing

The plugin turns off geometry propagation for the main window. All it does is:

pack propagate . false

This helps make the window the same size as the HTML width and height specifiers in the <embed> tag. Tclets you write should still work if they depend on the grid geometry manager, but in that case, you'll have to size the window yourself.

grid propagate . false