Tabbed MDI Child Forms

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Introduction

MDI child forms on tab page like Internet Explorer 7. So easy to use and a little code necessary.

Using the code

First, set isMDIContainer property of the parent form to true. Add a TabControl component to the main form and set the Dock property to Top. Delete all tab pages of TabControl and set the Name property to tabForms and set the Visible property to false.

No any code necessary for child forms. All codes in main forms.

When the MDI Child Form is activated; if child form has a tab page, activate the corresponding tab page else create a tab page for child form and select tab page.

private void Form1_MdiChildActivate(object sender, 
                                    EventArgs e) 
{ 
    if (this.ActiveMdiChild == null) 
        tabForms.Visible = false; 
        // If no any child form, hide tabControl 
    else 
    { 
        this.ActiveMdiChild.WindowState = 
        FormWindowState.Maximized; 
        // Child form always maximized 

        // If child form is new and no has tabPage, 
        // create new tabPage 
        if (this.ActiveMdiChild.Tag == null) 
        { 
            // Add a tabPage to tabControl with child 
            // form caption 
            TabPage tp = new TabPage(this.ActiveMdiChild
                                     .Text); 
            tp.Tag = this.ActiveMdiChild; 
            tp.Parent = tabForms; 
            tabForms.SelectedTab = tp;
            
            this.ActiveMdiChild.Tag = tp; 
            this.ActiveMdiChild.FormClosed += 
                new FormClosedEventHandler(
                                ActiveMdiChild_FormClosed); 
        }

        if (!tabForms.Visible) tabForms.Visible = true;

    }
}

When the MDI Child Form is closing, destroy the corresponding tab page. Add the following code to main form.

private void ActiveMdiChild_FormClosed(object sender, 
                                    FormClosedEventArgs e)
{
    ((sender as Form).Tag as TabPage).Dispose(); 
}

When a tab page selected, activate its child form

private void tabForms_SelectedIndexChanged(object sender, 
                                           EventArgs e) 
{ 
    if ((tabForms.SelectedTab != null) && 
        (tabForms.SelectedTab.Tag != null)) 
        (tabForms.SelectedTab.Tag as Form).Select(); 
}