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TkComponent allows you to create desktop UIs in Ruby, using a component structure taking advantadge of Tk, the UI toolkit created for TCL and used by Python in TkInter.

GIF demo

See example app using it at FunctionGrapher

TkComponent is also used in TkInspect, a gem to provide a Smalltalk-like GUI environment for Ruby.

WARNING Still very much a work in progress!


Add this line to your application's Gemfile:

gem 'tk_component'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tk_component

Why TkComponent?

TkComponent uses Tk bindings for Rails underneath, and provides a higher level API that should make things easier for Ruby GUI developers, by allowing them to:

  • Use the nesting structure of the code to define the structure of the widgets in the UI, mimicking HTML UIs built with nested markup.

  • Provide more convenient widget configuration, including layout and event handlers, hopefully less verbose than plain Tk.

  • Support the creation of self-contained components that can be used as building blocks when creating complex UIs.

Documentation is very lacking at that point. Best you can do is check some examples:

Getting started

You build TkComponent apps out of windows and components.

At a minimum you will need a root window to show your app, and a root component to be placed in that window.

#!/usr/bin/env ruby

require "tk_component"

class MyComponent < TkComponent::Base
  def render(p, parent_component)
    p.vframe(sticky: 'wens', padding: '4', x_flex: 1) do |f|
      f.label(text: "Name", sticky: 'w')
      f.hframe(sticky: 'ew', x_flex: 1) do |hf|
        @input = hf.entry(width: 8, sticky: 'we', x_flex: 1)
        hf.button(text: "Greet", on_click: :say_hello)
      @res = f.text(width: 20, height: 4, sticky: 'ewns', x_flex: 1, y_flex: 1)

  def say_hello(e)
    @res.tk_item.value = "Hello #{@input.tk_item.value}"

tk_root = "Demo", root: true)
main_component =


More details to come!

Ruby/Tk docs

TkComponent is a layer on top of Tk, but it still uses native Tk concepts and calls, so you'll need to be familiar with that.

Sources of documentation:

Installing Tk

TkComponent needs Tk to run. Depending on your system, you will need to install additional software for that.

You can find a good source of updated information about installing Tk here

Some additional details


You need to install Tcl/Tk in your Mac.

In earlier versions of macOS the needed libraries were already there, but that is not the case for newer versions (Mojave and later for sure).

Right now, it it seems that the best option is, ATM, the community edition of ActiveState at

After installation everything should run just fine.


WARNING This is the result of just some tests. It will be uodated when we get more solid information. Nevertheless, again refer to as a much more reliable source of installation information.

That said, in our experience so far, the best way to have Tk working o Linux is using ActiveState's community edition, just like with the Mac.


Josep Egea

Why this?

I feel that Ruby is a fantastic language for building GUI's.

It's expressive, flexible and easy to read. GUI's spend most of their time waiting for user input, so the actual performance of the language is not as important as the power it gives to the developer. To that avail, Ruby is a great fit, a true successor of Smalltalk, which was tightly integrated with a great GUI.

However, there's not much current GUI work in Ruby land. Most of developments happen in server side code, APIs and, of course, Rails.

Cause or consequence of this, the state of tools for GUI development in Ruby could be improved. Tk has always been kind of the official GUI environment for Ruby (as Tkinter is for Python), but the way you write GUI code in Tk for Ruby is quite verbose and very different from the current trends on how web GUI's are written.

I would love to write and see more Ruby GUI apps so I started on TkComponent as a way to have a more modern way of using the Ruby and Tk.

If you feel the same, I wish you find TkComponent useful. If you want to make it grow, your contributions will be quite welcome.

You can hear me talk more about these ideas in this talk I gave in the Madrid Ruby Users Group on January 2021.


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the TkComponent project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.


A Ruby gem to build desktop UIs using TK in a component-like fashion



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