Unfortunately, it is not possible to add a QComboBox as a topLevelItem in a QTreeWidget. The reason for this is that topLevelItems are meant to be headers or root items in the tree widget and do not have the capability to display widgets like child items.
However, you can achieve similar functionality by using a separate QWidget (e.g., a QGroupBox) as the parent widget for your QTreeWidget and adding the QComboBox as one of its child widgets. Here’s an example:
// create parent widget
QGroupBox* groupBox = new QGroupBox(this);
groupBox->setTitle("Top Level Item");
setCentralWidget(groupBox);
// create combo box
QComboBox* comboBox = new QComboBox(this);
comboBox->addItem("Option 1");
comboBox->addItem("Option 2");
// create tree widget
QTreeWidget* treeWidget = new QTreeWidget(groupBox);
treeWidget->setHeaderLabels({"Column 1", "Column 2"});
// add combo box and tree widget to parent widget
QVBoxLayout* layout = new QVBoxLayout(groupBox);
layout->addWidget(comboBox);
layout->addWidget(treeWidget);
// add child items to tree widget
QTreeWidgetItem* item1 = new QTreeWidgetItem(treeWidget);
item1->setText(0, "Item 1");
item1->setText(1, "Value 1");
QTreeWidgetItem* item2 = new QTreeWidgetItem(treeWidget);
item2->setText(0, "Item 2");
item2->setText(1, "Value 2");
In this example, we first create a parent QWidget (in this case, a QGroupBox) and set it as the central widget of our main window. We then create a QComboBox instance and add some options to it.
Next, we create the tree widget and set its header labels. We also create a QVBoxLayout instance for our parent widget and add the QComboBox and tree widget to it.
Finally, we add some child items to our tree widget. When you run your application, you should see a QGroupBox with a QComboBox and a QTreeWidget embedded within it.
