-------------------------------------------------------------
WinForm 需要添加 对System.Windows.Forms的引用
------------------------
if (MessageBox.Show("123", "caption", MessageBoxButtons.YesNo) == DialogResult.Yes)
{
}
else
{
}
-------------------------------------------------------------
WPF 需要添加 对WindowsBase、System.Xaml、 PresentationCore 和 PresentationFramework的引用
------------------------
if (MessageBox.Show("123", "caption", MessageBoxButtons.YesNo) == MessageBoxResult.Yes)
{
}
else
{
}