C#

private bool func_called = false;

private void VocNoTextBox_KeyDown(object sender, KeyEventArgs e)
{
   if (e.KeyData.Equals(Keys.Enter))
   {
      MoveToSpecificVocNo();
      func_called = true;     // <---
   }
}

private void VocNoTextBox_Leave(object sender, EventArgs e)
{
   if ( !func_called )
   {
      MoveToSpecificVocNo();
   }

   func_called = false;     //<---
}

private void VocNoTextBox_KeyDown(object sender, KeyEventArgs e)
{
   if (e.KeyData.Equals(Keys.Enter))
   {
      SendKeys.Send ( "\t" );
   }
}

public abstract class Channel
    {
        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(false)]
        [DescriptionAttribute("If set to True, the oscilloscope acquires a waveform for the channel.  If set to False, the oscilloscope does not acquire a waveform for the channel")]
        public abstract bool ChannelEnabled { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(false)]
        [DescriptionAttribute("Specifies whether channel is inverted or not")]
        public abstract bool ChannelInverted { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Returns the physical repeated capability identifier defined by the specific driver for the channel that corresponds to the one-based index that the user specifies.  If the driver defines a qualified channel name, this property returns the qualified name")]
        public abstract double ChannelName { get; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies the input impedance for the channel in Ohms. Common values are 50.0, 75.0, and 1,000,000.0")]
        public abstract double InputImpedance { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies the maximum frequency for the input signal you want the instrument to accommodate without attenuating it by more than 3dB")]
        public abstract double MaximumInputFrequency { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies the scaling factor by which the probe the end-user attaches to the channel attenuates the input.  For example, for a 10:1 probe, the end-user sets this attribute to 10.0")]
        public abstract double ProbeAttenuation { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies how the oscilloscope couples the input signal for the channel")]
        public abstract VerticalCoupling VerticalCoupling { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies the location of the center of the range that the Vertical Range attribute specifies. The value is with respect to ground and is in volts")]
        public abstract double VerticalOffset { get; set; }

        [Category("IviScopeBase Capability Group")]
        [DefaultValueAttribute(0)]
        [DescriptionAttribute("Specifies the absolute value of the full-scale input range for a channel. The units are volts")]
        public abstract double VerticalRange { get; set; }

        [Category("IviScopeProbeAutoSense Extension Group")]
        [DefaultValueAttribute(false)]
        [DescriptionAttribute("If this attribute is True, the driver configures the oscilloscope to sense the attenuation of the probe automatically. If this attribute is False, the driver disables the automatic probe sense and configures the oscilloscope to use the value of the Probe Attenuation attribute")]
        public abstract bool ProbeAttenuationAuto { get; set; }
    }

public abstract List<Channel> Channels { get; set; }

public override List<Channel> Channels
{
    get
    {
        throw new NotImplementedException();
    }
    set
    {
        throw new NotImplementedException();
    }
}

VisaOscilloscope myScope = new VisaOscilloscope();
myScope.channels[0].Enabled = true;

void InitChannels()
{
   List<Channel> newChannels = new List<Channels>

   int channelId = 1;
   newChannels.Add(new AnalogChannel(this, channelId));

   ++channelId;
   newChannels.Add(new AnalogChannel(this, channelId));
   
   int digitalChannels = 16;
   for (int i = 0; i != digitalChannels; ++i)
   {
      ++channelId;
      newChannels.Add(new DigitalChannel(this, channelId);
   }

   ++channelId;
   newChannels.Add(new ClockChannel(this, channelId);

   ++channelId;
   newChannels.Add(new TriggerChannel(this, channelId);

   // Update oscilloscope channels...
   Channels = newChannels;
}

visaoscilloscope myscope = new visaoscilloscope();
string ID = myscope.ID;

public override string ID
        {
            get { return myTk.GetString(tktds1k2kProperties.IdQueryResponse); }
        }

interface IOscilloscopeForChannels 
{
  bool IsChannelEnabled(string channelId);
  //...
}

var oscilloscope1 = GetTheOscilloscope();

/// Get a reference to the channel we want to uses
var channel3 = oscilloscope1.Channels["ch3"]; // Channels could be a dictionary

// Uses that channel in code.
// The channel might forward the call to the oscilloscope class.
channel3.IsEnabled = true;
AddToView(channel3.CurrentValue);
channel3.IsEnable = false;