Question

I have a Windows Forms application that opens MDI child forms. When I select those forms, I need to set or render its windowstate to Maximized. The problem is, when I navigate between the open forms, it reverts back to the normal window state, and when I set the window state to maximized again, it shows the transition from normal to maximized state and it doesn’t look nice.

How can a Windows application be created that have an MDI parent form that opens many MDI childs in maximized window state?

Answer 1

Here’s an answer based on using the MDI “Parent Form and Child Form paradigm,” with the following assumptions :

1. you have a MenuStrip control ‘Dock = ‘Top on your MDIParentForm, and you’ve implemented the automatic MDI &Window menu handler as described in : How to: Create an MDI Window List with MenuStrip

2. you are creating new child forms that :

   a. do not have a MaximizeBox, MinimizeBox, etc., but may have ControlBox (for closing them)

   b. these child forms may be resizable or not : we won’t consider the implications of that here.

3. You want these MDIChildForms to display maximized in the MDIParent Form, but not to obscure the MDIParentForm’s menu.

Okay : assuming you have all your child Forms fully designed, “waiting in the wings” : we might see some code like this in your MDIParentForm code :

    // create instances of your child forms
    Form2 f2 = new Form2();
    Form3 f3 = new Form3();
    Form4 f4 = new Form4();
    Form5 f5 = new Form5();

    private void MDIParentForm1_Load(object sender, EventArgs e)
    {
        f2.Text = "subForm1";
        f3.Text = "subForm2";
        f4.Text = "subForm3";
        f5.Text = "subForm4";

        f2.MdiParent = this;
        f3.MdiParent = this;
        f4.MdiParent = this;
        f5.MdiParent = this;

        f2.Dock = DockStyle.Fill;
        f3.Dock = DockStyle.Fill;
        f4.Dock = DockStyle.Fill;
        f5.Dock = DockStyle.Fill;

        f2.Show();
        f3.Show();
        f4.Show();
        f5.Show();
    }

At this point, the dock style ‘Fill applied to the child forms will make them full-screen, and keep them from obscuring the MDIParentForm menu : and the menu will allow you to auto-select which one is frontmost.

Now, if you want to do fancier stuff : like resizing the child Forms, tiling them, cascading them. You are going to have to change the ‘Dock property of these child windows : and then you can make use of the built-in MDI paradigm window arranging facilities as described here : How to: Arrange MDI Child Forms

And if you want to create multiple instances of one type of pre-defined child form : How to Create MDI Child Forms … see the example on how to use a ‘New menu entry : may prove useful.