主题：如何通过代码判断某个TabPage为当前选择的页面？

Dim tc As WinForm.Control = Forms("窗口").Controls("TabControl1")
Dim pg1 As WinForm.TabPage = Forms("窗口").Controls("TabControl").TabPages("TabPage1")
Dim pg2 As WinForm.TabPage = Forms("窗口").Controls("TabControl2").TabPages("TabPage2")
Dim pg3 As WinForm.TabPage = Forms("窗口").Controls("TabControl2").TabPages("TabPage3")

要求，当"TabPage1"为"TabControl1"的激活页面时，

"TabPage2"显示，否则"TabPage3"显示。

求代码，谢谢。