Tcl/Tk developers have constructed many interesting widget sets which extend Tk's basic functionality. A few of these--Tix, for example--are reasonably well known and accessible to Tkinter users. What about the rest? When a TkInter programmer sees a promising Tk extension, is it likely to do him or her any good?

Briefly, yes. First, it's important to make the distinction between so-called "pure Tk" extensions and those that involve (external) C-coded compilation. Quite a few useful widgets sets, most notably including BWidgets and tklib, are "pure Tk". That means that Tcl/Tk programmers simply read them in at run time, with no need for (re-)compilation, configuration, or other deployment complexities.

These extensions are nearly as easy for TkInter programmers to use. Here's an example:

If you have a file of Tcl code in a file called foo.tcl and you want to call the Tcl function foo_bar then

    import Tkinter
    root = Tkinter.Tk()
    root.tk.eval('source {foo.tcl}')
    root.tk.eval('foo_bar')

will load and execute foo_bar. To see the details of passing and returing arguments, Use the Source Luke, and look at Lib/lib-tk/Tkinter.py. For wrappers of other popular Tk widgets, look at the Python/ directory of the Tixapps distribution https://tix.sourceforge.net/Tixapps/

On the other hand, Tix and BLT are popular Tk extensions which require compilation. These days (since version 8.0 of Tk) most extensions are compiled as dynamic loading packages, and are as easy to load into Tkinter as pure Tk extensions using a Python expression like

    root.tk.eval('package require Ext')

For an example of this, see the Lib/lib-tk/Tix.py file in the standard library that loads the Tix extension.

The trick here is to install the extension library directory in a place the Tcl in TkInter will find it. The best place to try is as a subdirectory of Tcl/ in the Python installation. If this does not work, look into the file pkgIndex.tcl in the extension's library directory and try to understand what it is doing to load the .dll or .so shared library. To ask Tcl to consider a specific directory that contains a package, use

     root.tk.eval('lappend auto_path {%s}' % the_tcl_directory)

FredrikLundh has pages which he calls "work in progress", but which readers are certain to find helpful: https://effbot.org/zone/bwidgets.htm and https://effbot.org/zone/tkinter-text-bind-insert-delete.htm The latter explicitly extends Tkinter through use of Tcl. Also, Gustavo Cordero is working in this same area; his work is likely to show up in the Tcl-ers' Wiki for Tkinter.