.net – Detecting user presence

I liked Mark Brackett's answer so much that I did my own quick implementation. Here it is if anyone else needs it in a hurry:

public class NetworkConnection : IDisposable
{
    string _networkName;

    public NetworkConnection(string networkName, 
        NetworkCredential credentials)
    {
        _networkName = networkName;

        var netResource = new NetResource()
        {
            Scope = ResourceScope.GlobalNetwork,
            ResourceType = ResourceType.Disk,
            DisplayType = ResourceDisplaytype.Share,
            RemoteName = networkName
        };

        var userName = string.IsNullOrEmpty(credentials.Domain)
            ? credentials.UserName
            : string.Format(@"{0}\{1}", credentials.Domain, credentials.UserName);

        var result = WNetAddConnection2(
            netResource, 
            credentials.Password,
            userName,
            0);

        if (result != 0)
        {
            throw new Win32Exception(result);
        }   
    }

    ~NetworkConnection()
    {
        Dispose(false);
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
        WNetCancelConnection2(_networkName, 0, true);
    }

    [DllImport("mpr.dll")]
    private static extern int WNetAddConnection2(NetResource netResource, 
        string password, string username, int flags);

    [DllImport("mpr.dll")]
    private static extern int WNetCancelConnection2(string name, int flags,
        bool force);
}

[StructLayout(LayoutKind.Sequential)]
public class NetResource
{
    public ResourceScope Scope;
    public ResourceType ResourceType;
    public ResourceDisplaytype DisplayType;
    public int Usage;
    public string LocalName;
    public string RemoteName;
    public string Comment;
    public string Provider;
}

public enum ResourceScope : int
{
    Connected = 1,
    GlobalNetwork,
    Remembered,
    Recent,
    Context
};

public enum ResourceType : int
{
    Any = 0,
    Disk = 1,
    Print = 2,
    Reserved = 8,
}

public enum ResourceDisplaytype : int
{
    Generic = 0x0,
    Domain = 0x01,
    Server = 0x02,
    Share = 0x03,
    File = 0x04,
    Group = 0x05,
    Network = 0x06,
    Root = 0x07,
    Shareadmin = 0x08,
    Directory = 0x09,
    Tree = 0x0a,
    Ndscontainer = 0x0b
}

When you call GetDC, you get the DC for the client area. To get the DC for the whole window (including the non-client area title bar and border) use GetDCEx with the DCX_WINDOW flag.

Also, check out the PrintWindow function, it lets you take a snapshot of a window even if its obscured or partially off screen - its not perfect but it works pretty well.