MessageBox挂起

Question

在按winforms应用程序上的按钮时，我试图显示一个消息框，但是MessageBox挂起，永远不会返回值。

private void btnApply_Click(object sender, EventArgs e)
    {
        bool current = false;
        if (cmbEmergencyLandingMode.SelectedIndex > 0)
        {
            if (m_WantedData != false)
            {
                DialogResult dr = MessageBox.Show("Are you sure you want to enable Emergency Landing mode?", "Warning!", MessageBoxButtons.YesNo, MessageBoxIcon.Warning);

                //i never get to this point
                current = (dr == DialogResult.Yes);
            }
        }

        if (m_WantedData == current)
        {
            //do something
        }
        else if (m_WantedData != null)
        { 
            //do something else
        }
    }

编辑： Ok，所以我通过处理后台工作人员上的按钮事件来工作：

private void btnApply_Click(object sender, EventArgs e)
    {
        if (!bwApply.IsBusy) 
            bwApply.RunWorkerAsync(cmbEmergencyLandingMode.SelectedIndex);
    }

    void bwApply_DoWork(object sender, DoWorkEventArgs e)
    {
        bool current = false;
        int selectedIndex = (int)e.Argument;

        if (selectedIndex > 0)
        {
            if (m_WantedData != false)
            {
                DialogResult dr = MessageBox.Show(
                    "Are you sure you want to enable Emergency Landing mode?",
                    "Warning!", MessageBoxButtons.YesNo, MessageBoxIcon.Warning);
                current = (dr == DialogResult.Yes);
            }
        }

        if (m_WantedData == current)
        {
            //do something
        }
        else if (m_WantedData != null)
        {
            //do something else
        }
    }

感谢每一个帮忙的人！

Answer 1

您是否尝试指定消息框所有者，如下所示？

DialogResult dr = MessageBox.Show(
    this,
    "Are you sure you want to enable Emergency Landing mode?",
    "Warning!",
    MessageBoxButtons.YesNo,
    MessageBoxIcon.Warning);

如果在消息框后面显示消息框，同时对UI进行并发更改，那么应用程序就会出现这样的行为。如果上面没有帮助，尝试通过异步处理事件来减轻UI处理(即WinAPI消息传递)的压力，如下所示。

public delegate void ApplyDelegate();

private void btnApply_Click(object sender, EventArgs e)
{
   btnApply.BeginInvoke(new ApplyDelegate(ApplyAsync));
}

private void ApplyAsync()
{
    bool current = false;
    if (cmbEmergencyLandingMode.SelectedIndex > 0)
    {
        if (m_WantedData != false)
        {
            DialogResult dr = MessageBox.Show(
                this,
                "Are you sure you want to enable Emergency Landing mode?",
                "Warning!",
                MessageBoxButtons.YesNo,
                MessageBoxIcon.Warning);

            //i never get to this point
            current = (dr == DialogResult.Yes);
        }
    }

    if (m_WantedData == current)
    {
        //do something
    }
    else if (m_WantedData != null)
    { 
        //do something else
    }
}

Answer 2

在MessageBox.Show()方法中尝试在不分配父窗体的情况下显示消息。我不知道为什么，但是，当我加载模态窗口时，我也遇到了类似的问题。

if (m_WantedData != false)
{
    if (MessageBox.Show("Sample Message", "Are you sure you want to enable Emergency Landing mode?", "Warning!", MessageBoxButtons.YesNo, MessageBoxIcon.Warning) == DialogResult.Yes)
    {
        //DO YOUR STUFF HERE IF YES
    }
    else
    {

    }
}