C# 判断窗体是否打开
/**
* 判断窗体是否打开
* foreach (Form f in this.MdiChildren)
* Form f in Application.OpenForms
* if (from.IsDisposed || from.Created)
* */
/**
* 判断窗体是否打开
* foreach (Form f in this.MdiChildren)
* Form f in Application.OpenForms
* if (from.IsDisposed || from.Created)
* */