@#include <QtWidgets>
#include <QGLWidget>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QMainWindow w;

w.setCentralWidget(new QGLWidget(&w));

QTreeWidget* tree = new QTreeWidget(&w);
QTreeWidgetItem* item0 = 
    new QTreeWidgetItem(tree, QStringList("a"));
QTreeWidgetItem* item1 = 
    new QTreeWidgetItem(tree, QStringList("b"));
tree->setContextMenuPolicy(Qt::CustomContextMenu);
QObject::connect(
    tree,
    &QTreeView::customContextMenuRequested,
    [&](){
        QMenu menu;
        menu.addAction("a");
        menu.exec(QCursor::pos());
});

QDockWidget* dock = new QDockWidget("Tree", &w);
dock->setWidget(tree);
w.addDockWidget(Qt::LeftDockWidgetArea, dock);

w.show();
return a.exec();

}@

Compile and run it. It requires 2 right clicks to switch context menus among items. However, if I change QGLWidget to QWidget. It is fine. 1 right click can switch context menus among items. Any bugs??? Thanks a lot.

Some observations: Switch the positions of the tree and the GL widget is ok, i.e. set the tree as the central widget and GL Widget as the one in the dock.

More findings. When the widow is maximized. The issue is gone. When the widow is aligned with the left-top corner of the desktop screen, the issue is also gone. Thus, I think the bug is a mis-calculation of the mouse position when mapping to/from different widgets with dock widgets involved.

Hope to see it corrected in the next Qt release.