C# Windows Form disappears suddenly!

Question

Hello everyone,

I am using C# + VSTS2008 + .Net 2.0 to develop a Windows Forms application. In button1 event handler of Form1, I create Form2, then Form2 appears. Then when trigger event handler of button2 of Form2 (button2 is Form2's UI button element), after executing button2 event handler, Form2 will disappear. Here is part of my code which creates Form2. Any ideas what is wrong to cause Form2 disappear?

// button1 belongs to Form1
private void button1_Click(object sender, EventArgs e)
{
    Form2 form2 = new Form2("www.google.com");
    form2.ShowDialog();
}

thanks in advance, George

Answer 1

Without more details it's impossible to say for sure, but if button2 in Form2 has a value assigned to the DialogResult property, this will cause the form to hide automatically when the button is clicked. Open Form2 in the designer, select the button and check in the property grid. If the DialogResult property is anything else than "None", this is expected behaviour.

From the MSDN documentation of the Button.DialogResult property:

If the DialogResult for this property is set to anything other than None, and if the parent form was displayed through the ShowDialog method, clicking the button closes the parent form without your having to hook up any events. The form's DialogResult property is then set to the DialogResult of the button when the button is clicked.

Answer 2

Form2 is being opened as a dialog. Could the button being pressed also be defined as the CancelButton (The CancelButton property will be on form2). Doing that will automatically dismiss the dialog when the event handlers have completed.