You cannot eject a form by using SaveFileDialog in a thread

Using SaveFileDialog in a child thread does not eject the form, mainly because we need to use the main thread to process the SaveFileDialog,

We can set the sub-thread as follows:

public partial class Form1:form
{
Public Form1 ()
{
InitializeComponent ();
}

private void Button1_Click (object sender, EventArgs e)
{
Thread t = new thread (savedialog);
T.isbackground = true;

T.setapartmentstate (ApartmentState.STA);//The absence of this sentence will make a mistake.
T.start ();
}

public void Savedialog ()
{
SaveFileDialog result = new SaveFileDialog ();
Result. ShowDialog ();
}
}

Using SaveFileDialog in threads cannot eject a form