Computer Vision with OpenCV 3 and Qt5

Sub-controls

Or better yet, sub-widgets are the child widgets inside the complex widget. An example would be the down and up arrow buttons on a QPinBox widget. They can be selected with the :: operator, as seen in the following example:

    QSpinBox::down-button 

Always remember to refer to the Qt Style Sheets Reference article available in the Qt Creator Help mode for a (more or less) complete list of sub controls for each widget. Qt is an evolving framework and new functionalities are added on a regular basis so there's no better reference than its own documentation.