diag2

void MainWindow::InitComponents()
{
    QPoint p = pos();

    undoDialog = new UndoHistoryDialog(this);

    p += QPoint(this->width(), this->height()); // at this point p = (700, 600)
    p -= QPoint(undoDialog->width(), undoDialog->height()); // p = (460, 280)

    undoDialog->move(p);
    undoDialog->show();
}