install qt designer ubuntu code example
Example 1: install qt4-qmake ubuntu
sudo add-apt-repository ppa:rock-core/qt4
sudo apt update
sudo apt install qt4-default
sudo apt install qt4-qmake
#to remove it
sudo add-apt-repository --remove ppa:rock-core/qt4
Example 2: install qt designer python ubuntu
sudo apt-get install qttools5-dev-tools
sudo apt-get install qttools5-dev