Windows Forms - C#

First of all, 

Thanks so much for your time. I truly appreciate it.

Here is what I did, I followed your instructions and I applied the code for each form but unfortunately, the problem wasn't solved yet. So, are there any properties i need to change or set up in order for this code to work properly?

With Regards.  

You can use the Form.ResizeEnd event to handle this scenario.

1. n each of the forms, add an event handler for the ResizeEnd event. You can do this by selecting the form in the designer, going to the Properties window, and clicking the lightning bolt icon to show the events. Then, double-click the ResizeEnd event to generate the event handler method.

2. In the event handler method, check if the form is maximized using the FormWindowState enumeration. If it is maximized, iterate through all the other forms in your application and set their WindowState property to FormWindowState.Maximized as well.

Sample code:

private void Form1_ResizeEnd(object sender, EventArgs e)
{
    if (this.WindowState == FormWindowState.Maximized)
    {
        foreach (Form form in Application.OpenForms)
        {
            if (form != this)
            {
                form.WindowState = FormWindowState.Maximized;
            }
        }
    }
}

Thanks

Naimish Makwana