Install iwidgets4 by entering the following commands in the terminal:
sudo apt update sudo apt install iwidgets4
Description:
[incr Widgets] Tk-based widget collection - run-time files
[incr Widgets] (or iwidgets) is an object-oriented "mega-widget" set, or collection of high-level user-interface components, based on the popular Tk toolkit and the itcl/itk OO framework. Iwidgets contains over 50 ready-to-use mega-widgets including calendar, canvasprintdialog, combobox, fileselectiondialog, hyperhelp, notebook, radiobox, spinner, and many more.
Homepage: http://incrtcl.sourceforge.net/iwidgets/
Version: 4.1.0-1
Section: universe/libs