C1TrueDBGrid：如何为下拉菜单创建快捷键

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (keyData == (Keys.Shift | Keys.F1)) //Shortcut key to be used
    {
        if (ddstate == 0)
            shrtcutopen = 0;
 
        /*CODE TO OPEN THE DROPDOWNS IN THE GRID CELLS WITH SHORTCUT KEY {SHIFT+F1}*/
        if (shrtcutopen == 0)
        {
            SendKeys.Send("%{DOWN}");
            shrtcutopen = 1;
        }
 
        ++counter;
        /*CODE TO OPEN THE DROPDOWNS IN THE FILTERBAR WITH SHORTCUT KEY {SHIFT+F1}*/
        if (filter == 0)//&&  counter == 1)
        {
            if (c1TrueDBGrid1.FilterActive)
            {
                SendKeys.Send("%{DOWN}");
                filter = 1;
                shrtcutopen = 0;
            }
        }
       return false;
    }
    if (keyData == (Keys.Shift | Keys.F2)) //Shortcut key to be used
    {
        /*CODE TO CLOSE THE DROPDOWNS IN THE GRID CELLS WITH SHORTCUT KEY {SHIFT+F2}*/
        if (shrtcutclose == 1)
        {
            SendKeys.Send("%{UP}");
            shrtcutclose = 0;
 
        }
 
        /*CODE TO CLOSE THE DROPDOWNS IN THE FILTERBAR WITH SHORTCUT KEY {SHIFT+F2}*/
        if (filter == 1)
        {
            SendKeys.Send("%{UP}");
            filter = 0;
            shrtcutopen = 0;
        }
            return false;
    }
    if (keyData == Keys.Enter)
    {
        filter = 0;
    }
 
    return base.ProcessCmdKey(ref msg, keyData);
}