MDI Form detecting with a child form is added or removed

Question

Is there an event I can use to tell if a child form has been added or removed from the MDI parent?

Answer 1

I recently wanted to determine approximately when there were NO MDIchildren open so I could display a panel with lots of "things to do" buttons on it Only when there were no child forms open. (just exploring a design idea).

My eventual solution was elegantly simple - add a timer to the parent form and start the timer up whenever the MdiChildActivate event determined there was 1 child form open.

    private void MyForm_MdiChildActivate(object sender, EventArgs e)
    {
        this.panel_Tools.Visible = false;
        if (this.MdiChildren.Count() == 1)
        {
            this.timer_WindowsCounter.Start();
        }
        else
        {
            this.timer_WindowsCounter.Stop();
        }

    }


    private void timer_WindowsCounter_Tick(object sender, EventArgs e)
    {
        if (this.MdiChildren.Count() == 0)
        {
            this.panel_Tools.Visible = true;
            this.timer_WindowsCounter.Stop();
        }
    }