[1.0/1.1] Checking whether the form is disposed or not!

On a mdi's menu click i am calling a child form.

On the click event I want to check whether the form is already initiated. if not then i want to initiate it first and then call the show method. on closing the form i dispose it.

How to chk whether the form is disposed or not?

IsNothing is not working

I'm not sure whether you have resolved this or not but the code should look something like this:

C# Code:

private Form2 childForm;
 
private void ShowChildForm()
{
    if (this.childForm == null || this.childForm.IsDisposed)
    {
        // Create a new child form and show it.
        this.childForm = new Form2();
        this.childForm.MdiParent = this;
        this.childForm.Show();
    }
    else
    {
        // Activate the existing child form.
        this.childForm.Activate();
    }
}

Note that if there is not supposed to be more than one instance of a form then you can also have that form implement the Singleton pattern:

C# Code:

public partial class Form2 : Form
{
    private static Form2 _instance;
 
    public static Form2 Instance
    {
        get
        {
            if (_instance == null || _instance.IsDisposed)
            {
                _instance = new Form2();
            }
 
            return _instance;
        }
    }
 
    private Form2()
    {
        InitializeComponent();
    }
}

Then your code in the parent form becomes:

C# Code:

private void ShowChildForm()
{
    Form2.Instance.MdiParent = this;
    Form2.Instance.Show();
    Form2.Instance.Activate();
}