How can i change ClearCanvas DesktopForm application menu's visibility to false_

Question

i try to write a PACS application over ClearCanvas opensource sources. But i can everything over DestopForm only _mainmenu's visibility turn into false stage.

   // _mainMenu
            // 
            this._mainMenu.BackColor = System.Drawing.SystemColors.ActiveCaption;
            this._mainMenu.Dock = System.Windows.Forms.DockStyle.None;
            this._mainMenu.ImageScalingSize = new System.Drawing.Size(24, 24);
            this._mainMenu.Location = new System.Drawing.Point(0, 0);
            this._mainMenu.Name = "_mainMenu";
            this._mainMenu.Size = new System.Drawing.Size(792, 24);
            this._mainMenu.TabIndex = 4;
            this._mainMenu.Text = "menuStrip1";
            this._mainMenu.Visible = false;

i can do every form events. But visibility make me too sense.How can i do that?