C# winform this.Visible = false后出现一个短暂的白屏

你写了Thread.Sleep(1000);这一句，这个是让线程暂停1秒啊，你要不就另外写一个线程来执行，要不你就不要这一句试试

this.Visible = false;
this.pictureBox1.Visible = false;
this.pictureBox2.Visible = false;
这3句代码没必要写, 你可以在这三个控件的属性里面直接把visible设置成false；

this.Visible = false;
this.pictureBox1.Visible = false;
this.pictureBox2.Visible = false;
this.form2.hangupcall();
Application.DoEvents();
Thread.Sleep(1000);

this.Visible = true;
this.pictureBox1.Visible = true;
this.pictureBox2.Visible = false;