void QueueCoWork::Manage(Callback1 &cb)
{
    int mostFreeThread = -1;
    //find most free (unbusy) Thread

    queueThreads[mostFreeThread] << cb;
}

void QueueCoWork::ManageTypical(Callback1 &cb)
{
    //simply rotate through threads to average tasks count
    lastUsedThread = (++lastUsedThread) % queueThreads.GetCount();

    queueThreads[lastUsedThread] << cb;
}

//----------------------------------------------------
void MainWindow::OnPaint
{
    queueCoWork << THISBACK(PaintLines);
}

void MainWindow::PaintLines()
{
    for (int y=0; y<height; ++y)
        queueCoWork.ManageTypical(THISBACK1(PaintLine, y));
}
void MainWindow::PaintLine(int y)
{
    //paint the y-th line
}