private List<Control> _allControls = new List<Control>();

private void InitializeControlList()
        {
            Queue<Control.ControlCollection> q = new Queue<Control.ControlCollection>();
            q.Enqueue(this.Controls);

            while (q.Count > 0)
            {
                Control.ControlCollection controls = (Control.ControlCollection)q.Dequeue();
                if (controls == null || controls.Count == 0) continue;

                foreach (Control control in controls)
                {
                    q.Enqueue(control.Controls);

                    if (this.IsMdiChild)
                    {
                        if (control is System.Windows.Forms.ToolStrip || control is System.Windows.Forms.ToolStripDropDown)
                        {
                            continue;
                        }
                    }

                    this._allControls.Add(control);
                }
            }
        }