The form is exposed on Hide ()

Question

I have a C # WinForms application running on the .NET Framework 4.0.

When a user is inactive for a certain period of time, I want him to hide all displayed forms and show an icon in the notification area. When a user clicks on this icon, a login form appears, and if the credentials are valid, they open the exact forms that were opened before.

To do this, I save the list of open forms in objects Listfrom Formand hide them like this. This method is called by Timer :

private void LogOut()
{
    foreach (Form form in Application.OpenForms)
        if (form.Visible)
        {
            GlobalVariables.formList.Add(form);
            form.Hide();
        }
}

When the credentials are verified, I try to make the forms visible again, for example:

//Show the previous forms.
foreach (Form form in GlobalVariables.formList)
    form.Visible = true;

//Clear the forms list.
GlobalVariables.formList.Clear();

MainForm , , , . ( ShowDialog() MainForm), form.Visible = true; :

ObjectDisposedException was unhandled
Cannot access a disposed object

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Answer 1

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Answer 2

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private void button1_Click(object sender, EventArgs e)
{
    Form1 f1 = new Form1();
    f1.ShowDialog();
}

private void button2_Click(object sender, EventArgs e)
{
    Hide();
}

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    MessageBox.Show("Closing");
}

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Answer 3

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using (var theForm = new CreateInvoice())
{
    theForm.ShowDialog();

    if (theForm.Updated)
    {
        GetInvoiceStatus();
    }
}

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Answer 4

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