Tab based MDI from

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();
}