兄弟前些日子做项目，第一次使用vb.net，碰上不少问题，相信很多初学者多多少少都会遇到这些问题，为了初学者学习方便，小弟总结了一些小经验，供大家参考讨论。
第一篇：如何在MDI子窗体中控制父窗体的属性等等
    功能：比如打开一个子窗体后，就要设置父窗体中的某个菜单项或者按钮为不可见状态，诸如此类。
    内容：
MDI父窗体和MDI子窗体类定义如下：
MDI父窗体：
Class MDIForm
        Inherits System.Windows.Forms.Form
.........
        'member mnuMain  
        Friend WithEvents mnuEditPaste As System.Windows.Forms.MenuItem
.......
        'member  
        Friend WithEvents toolScan As System.Windows.Forms.ToolBarButton
        private sub showChild()
            dim frmTmp as new MDIChildFom'define a new instantce of MDIChildForm
            frmTmp.MdiParent = me                'set  the new form to be a Mdichild
            frmTmp.show()                                'show the new form
        end sub
end Class
MDI子窗体：
Class MDIChildForm
.......
   'set mnuEditPaste &  toolScan  cannot be seen 
   private sub setMDIMnuToolUnvisible()
        '***************************************'
        ' first method you can set a menuitem to be unvisible'
        '***************************************'
        'this method you could not control one  MenuItem
        'you can only set a group of menuitems
        me.MdiParent.Menu.Menuitems(0).visible = False       'set the first group menuitem can not be seen 
        'with this method you have not right to modify toolScan

        dim frmMdi as MDIForm
        if tyhpeof me.MdiParent  is MDIForm
            frmMdi = DirectCast(me.Mdiparent, MDIForm)'get the instantce of me.MdiParent
                                            'then you should access all the members of class MDIForm without private members
            frmMdi.mnuEditPaste  = False
            frmMdi.toolScan  = Flase
            'like this you could do everything with MDIForm you want
        end if
               
    end sub
end Class