/// <summary>
/// 打开子窗体（已存在同类窗体时，不再重复打开，而是显示已有的窗体）
/// </summary>
/// <param name="newform">已经实例化的子窗体</param>
/// <param name="openDifTextForm">是否打开标题不同的同一类型窗体</param>
public static void ShowSizableForm(ChildSizableForm newform, bool openDifTextForm = false)
{
if (newform == null)
{
return;
}
if (newform.HasShow)
{
var forms = Application.OpenForms.Cast <Form>().Where(v => v.GetType().Equals(newform.GetType()));
//已show过同类窗体，并且允许比较窗体标题且标题不相同：建立新窗体
if (openDifTextForm && !forms.Any(v => v.Text.Equals(newform.Text)))
{
newform.Show();
}
else//销毁新窗体，显示旧窗体
{
newform.Close();
newform.Dispose();
Form form = forms.FirstOrDefault(v => v.Text.Equals(newform.Text));
if (form != null && form.WindowState == FormWindowState.Minimized)
{
form.WindowState = FormWindowState.Normal;
form.BringToFront();
}
}
}
else//未显示过同类型窗体时，显示新窗体
{
newform.Show();
}
}