在textbox里放按钮并控制输入字符不能覆盖住按钮(包括设计阶段)[4]

 private sub btn_mouseleave(byval sender as object, byval e as system.eventargs) handles btn.mouseleave

        cursor = cursors.ibeam

    end sub

 protected overrides sub wndproc(byref m as system.windows.forms.message)

 protected overrides sub wndproc(byref m as system.windows.forms.message)

        dim keyasc as integer = m.wparam.toint32

        select case m.msg

            case &h102

                if checklength() then

                    if keyasc <> 8 then