how to check if a non-modal dialog is already launched

Question

My application launches a non-modal dialog on a button click. If user clicks on that button again, I would like to do a check if that form is already running and wonder if its possible?

score 4 · Accepted Answer · answered Nov 21 '13 at 16:08

4

You can use Application.OpenForms Property

if (Application.OpenForms.OfType<YourNonModalFormType>().Any())
   // one is already opened

If you want to close this form:

var form = Application.OpenForms.OfType<YourNonModalFormType>().FirstOrDefault();
if (form != null)
{
    // launched
    form.Close();
}

answered Nov 21 '13 at 16:08

Sergey Berezovskiy

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thanks. If its already launched, can I close it through this way? – crazy novice Nov 21 '13 at 16:09
Actually i am using .net 3.5. Seem like it cannot be utilized in my code. Any other ways of doing it? – crazy novice Nov 21 '13 at 16:14
i guess i can always loop through the Application.OpenForms collection and compare its type with that of my non-modal form type – crazy novice Nov 21 '13 at 16:21
2

Are you just missing a `using System.Linq;` ? – sgmoore Nov 21 '13 at 16:22
@PaulSnow yep, sorry was busy. And yes, sgmoore is right - LINQ is available since .NET 3.5 – Sergey Berezovskiy Nov 21 '13 at 16:25
Is there a way to do a helper function out of this? How do i parameter the type/class of the form? – John Thompson Nov 16 '22 at 08:10

score 0 · Answer 2 · answered Nov 21 '13 at 16:36

Another approach is to manually declare a variable to track your form instance:

public partial class Form1 : Form
{

    public Form1()
    {
        InitializeComponent();
    }

    private Form2 f2 = null;

    private void button1_Click(object sender, EventArgs e)
    {
        if (f2 == null || f2.IsDisposed)
        {
            f2 = new Form2();
            f2.Show();
        }
        else
        {
            f2.Close();
        }
    }

}

how to check if a non-modal dialog is already launched

2 Answers2