How to prevent opening of two instances?

Hi,

What's the best way to prevent opening of two instances (or more) of the application?

Thanks

Check the single-instance box in the project property pages.

Thanks. Where is it exactly? I can't find it...

Is this a Windows Forms Application project, as I am assuming? If so the box is there in the project properties and if you look you'll find it. If it's not a WinForms app then there is no such box and you'd have to handle it manually.

OK, I see that I have to enable application framework and then I can set the single instance.
What is the affect of "enable application framework"?

You can see that I'm a newbie in VB.NET. I'm coming from VB6 and C++

The application framework should be enabled by default for new projects. Was your project upgraded from VB6 or VB.NET 2002/2003? If not then you must have disabled the application framework explicitly.

The application framework exists to do things like this. It will manage single-instance apps, splash screens, etc. for you so you don't have to write fiddly code to perform common application-based tasks. With the framework enabled the Main method is hidden from you and you handle application-level events, e.g. Startup and Shutdown, to do things that you would otherwise have done in the Main method.

OK, I see that I have to enable application framework and then I can set the single instance.
What is the affect of "enable application framework"?

You can see that I'm a newbie in VB.NET. I'm coming from VB6 and C++