VS 2010 setting non-GUI class file as Component

I have an annoyance that has been occurring for quite some time with Visual Studio 2010. I have a class file that I have made which VS saves as type "Component" for no reason I can discern. If I forget and try to open the file, it looks for a designer which doesn't exist.

I have looked on Google and found some similar issues for VS 2005, but the problems seemed to be related to deriving from GUI component classes (listbox, combobox, etc). Th开发者_如何学运维is class does not do that.

The file is GpsUtilities.cs. It appears in the csproj file as follows, with SubType of Component. No other references to the file exist, i.e. nothing claims it as DependentUpon.

<Compile Include="Utilities\GpsUtilities.cs">
  <SubType>Component</SubType>
</Compile>

Even if I remove the SubType tag, and even if I explicitly set it to Code instead of Component, it still saves it as SubType of Component.

Here is the class structure (all the code stripped out). As I said, it does not inherit, or even import the namespace of, anything GUI-related.

using System;
using System.ComponentModel;
using System.IO.Ports;
using System.Text.RegularExpressions;
using System.Timers;
using System.Xml.Serialization;

namespace AppNamespace
{
    public class GpsUtil : INotifyPropertyChanged
    {
        public GpsUtil() { }

        public static GpsUtil CreateInstance() { }

        public bool IsGpsReady { get; }

        public GPSPort GpsSerialPort { get; private set; }

        public Timer GpsTimer { get; set; }

        private CircularArray<GpsPositionData> PositionBuffer { get; set; }

        private GpsPositionData m_GpsCurLoc;

        public GpsPositionData MyLocation { }

        public string GpggaPattern { get; set; }

        public Regex GpggaRegEx { get; set; }

        public GpsPositionData GpsPosDataFromRegExMatch(Match gpsRegExMatch) { }

        public void SetGpsPosition(double latitude, double longitude) { }

        private void gpsTimer_Elapsed(object sender, ElapsedEventArgs e) { }

        private bool InitializeGpsPort() { }

        public bool TestGpsPort() { }

        public double ComputeSquaredDistance(double startLat, double startLon, double endLat, double endLon) { }

        public event PropertyChangedEventHandler PropertyChanged;
    }

    public class GPSPort : SerialPort
    {
        public GPSPort(string portName, int baudRate = 9600) : base(portName, baudRate)
        {
        }

        private bool TestResult { get; set; }

        public bool Test(int interval = 3000, bool leavePortOpen = false) {}
    }

    public enum GpsFixQuality { Invalid = 0, GpsFix = 1, DgpsFix = 2 }

    [Serializable]
    public class GpsPositionData
    {
        public GpsPositionData() { }

        public GpsPositionData(double latitude, double longitude) {}

        public override string ToString() {}

        public bool IsCloseTo(GpsPositionData otherPoint, double tolerance = 0.0001) {}

        public GpsPositionData(DateTime time, double latitude, double longitude, GpsFixQuality fixQuality, int numberOfSatellites, double hdop, double altitude, double geodialSeparation, int ageOfDgps, string dgpsRefStationId){}

        [XmlIgnore]
        public DateTime Time { get; private set; }

        [XmlElement("Latitude", typeof(double))]
        public double Latitude { get; set; }

        [XmlElement("Longitude", typeof(double))]
        public double Longitude { get; set; }

        [XmlIgnore]
        public GpsFixQuality FixQuality { get; private set; }

        [XmlIgnore]
        public int NumberOfSatellites { get; private set; }

        [XmlIgnore]
        public double Hdop { get; private set; }

        [XmlIgnore]
        public double Altitude { get; private set; }

        [XmlIgnore]
        public double GeodialSeparation { get; private set; }

        [XmlIgnore]
        public int AgeOfDgps { get; private set; }

        [XmlIgnore]
        public string DgpsRefStationId { get; private set; }
    }
}

Thanks in advance.

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If you want to keep all the classes in one file, you can use the [System.ComponentModel.DesignerCategory("Code")] attribute on the GPSPort class to override the default behavior. Details here, note that you must use the fully qualified attribute even if you have a using System.ComponentModel statement or VS will ignore it.

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At a guess, I'd say it's due to your GPSPort class, which extends SerialPort, which extends Component. Try removing that (or moving it into a separate file) and see if it fixes the problem.