Hi, After another look at the Bug I sent, I found out, that the real Problem lies in QAbstractScrollArea. If the QAbstractScrollArea is hidden while the custom QScrollButton is inserted, the show() method of the QScrollButton must be called to make it visible.
The attachment demonstrates the behavior
#include <QApplication> #include <QScrollArea> #include <QScrollBar> int main(int argc, char **argv) { QApplication app(argc, argv); QScrollArea *flawed = new QScrollArea(); flawed->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn); flawed->setWindowTitle("flawed"); QScrollArea *correct = new QScrollArea(); correct->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn); correct->setWindowTitle("correct"); // relevan start flawed->setVerticalScrollBar(new QScrollBar()); flawed->show(); correct->show(); correct->setVerticalScrollBar(new QScrollBar()); // relevant end app.exec(); }