Here’s the second part of our exploration of GUI toolkits for Common Lisp. The first part and introduction is accessible here: part 1: Ltk This blog post series was initially written for the Common Lisp Cookbook, you can (and should) read it there: https://lispcookbook.github.io/cl-cookbook/gui.html Qt4 (Qtools) Do we need to present Qt and Qt4? Qt is huge and contains everything and the kitchen sink. Qt not only provides UI widgets, but numerous other layers (networking, D-BUS…).