TextBox控件按Enter或Ctrl+Enter键发送消息的实现

// txtSendMsg为消息输入的TextBox控件
// txtReceive为消息接收的TextBox控件   
// 在txtSendMsg控件的KeyUp事件里处理。
       
// 按Enter发送
            if (isEnter)
            {
                if ((e.KeyData == (Keys.Control | Keys.Enter)))  // Ctrl+Enter
                {
                    txtSendMsg.SelectionStart = txtSendMsg.TextLength;
                } 
                else if (e.KeyCode == Keys.Enter)                // Enter
                {
                    txtReceive.Text += txtSendMsg.Text;
                    txtSendMsg.Clear();
                }
            }
            else   // 按Ctrl+Enter发送
            {
                if (e.KeyData == (Keys.Control | Keys.Enter))    // Ctrl+Enter
                {
                    txtReceive.Text += txtSendMsg.Text;
                    txtSendMsg.Clear();
                }
                else if (e.KeyCode == Keys.Enter)                // Enter
                {
                    txtSendMsg.SelectionStart = txtSendMsg.TextLength;
                }
            }