http://www.codeproject.com/KB/dotnet/windowsappsingleinstance.aspx
我刚学VB2005,正在看MSDN,看到下面例子,不知对你有用吗?
For Each f As Form In My.Application.OpenForms
下面是MSDN的地址
ms-help://MS.MSDNQTR.v80.chs/MS.MSDN.v80/MS.VisualStudio.v80.chs/dv_vbcn/html/cd85c380-837f-4419-86c4-48fd1070d88a.htm