Install libqt4-designer by entering the following commands in the terminal:
sudo apt update sudo apt install libqt4-designer
Description:
Qt 4 designer module
Qt is a cross-platform C++ application framework. Qt's primary feature is its rich set of widgets that provide standard GUI functionality. . The QtDesigner module provides classes that allow you to create your own custom widget plugins for Qt Designer, and classes that enable you to access Qt Designer's components.
Homepage: http://qt-project.org/
Version: 4:4.8.7+dfsg-7ubuntu1
Section: universe/libs