#include <QApplication>#include <QTreeWidget>
int main(int argc, char* argv[]){    
    QApplication app(argc, argv);    

    app.setStyleSheet(R"(
QAbstractItemView { color: #DCDCDC;  background-color: #1E1E1E;  alternate-background-color: #262626;  border-color: #3F3F46; }
QAbstractItemView::item:selected,QAbstractItemView::item:selected:hover { background-color: #3399FF;  color: #F1F1F1; }
QTreeView::indicator { background-color: #2D2D30;  border-color: #3F3F46;  width: 13px;  height: 13px;  border-style: solid;  border-width: 1px; }
QTreeView::indicator { width: 15px;  height: 15px; }
    )");
   
    QTreeWidget *w = new QTreeWidget();    
    w->setAlternatingRowColors(true);    
    
    QTreeWidgetItem *wa = new QTreeWidgetItem({"a"}),        
        *wb = new QTreeWidgetItem({"b"});

    wa->setCheckState(0, Qt::CheckState::Unchecked);    
    wb->setCheckState(0, Qt::CheckState::Checked);    

    w->addTopLevelItems({wa, wb});    
    w->show();
    
    return app.exec();
}