内部函数:项目_MainPages_CloseClick
'处理MainPages的自定义关闭按钮的点击事件
msgbox(_SysCloseBut.pg.name)
Dim tad = _SysCloseBut.pg.Parent
For i As Integer = 0 To tad.TabPages.Count - 1
If tad.TabPages(i).Name = _SysCloseBut.pg.name AndAlso i > 0 Then
tad.SelectedTab = tad.TabPages(i-1)
Exit For
End If
Next
tad.tabPages.Remove(_SysCloseBut.pg)