WPF

<Button Content="_OK" ... Command="{Binding Path=OKCommand}">
    <Button.Style>
        <Style TargetType="{x:Type Button}">
            <Setter Property="IsEnabled" Value="false" />
            <Style.Triggers>
                <MultiDataTrigger>
                    <MultiDataTrigger.Conditions>
                        <Condition Binding="{Binding ElementName=cascadingComboFrom, Path=(Validation.HasError)}" Value="false" />
                        <Condition Binding="{Binding ElementName=cascadingComboTo, Path=(Validation.HasError)}" Value="false" />
                    </MultiDataTrigger.Conditions>
                    <Setter Property="IsEnabled" Value="true" />
                </MultiDataTrigger>
            </Style.Triggers>
        </Style>
    </Button.Style>
</Button>

public partial class ucFC6SensorPictureBox : PictureBox
{
    private Color _BackgroundColor = Color.Yellow;
    public Color BackgroundColor
    {
        get
        {
            return _BackgroundColor;
        }
        set
        {
            _BackgroundColor = value;
            Refresh();
        }
    }

    public ucFC6SensorPictureBox()
    {
        InitializeComponent();
    }

    private void ucFC6SensorPictureBox_Paint(object sender, PaintEventArgs e)
    {
        // draw elipse with icon background color
        using (SolidBrush b = new SolidBrush(_BackgroundColor))
        {
            e.Graphics.FillEllipse(b, 1F, 1F, this.ClientRectangle.Width - 2F, this.ClientRectangle.Height - 2F);
        }

        if (Image != null)
        {
            e.Graphics.DrawImage(Image, new Point(0, 0));
        }
    }
}

1. The user can decide to show Hours, Minutes, or Seconds, or all three.
2. The content needs to scroll in relation to the scale shown... meaning if Minutes is selected, then every minute the scale needs to move from right to left the "width" of the space of one minute bar. The more ticks shown (seconds), the faster it moves.
3. The content area needs to be dragable. Once dragging is done, the control should resume responding to timer events.
4. There has to be a vertical bar that represents "now", and that bar should always be in the center. This should not be an issue since the control is moving in real time, so the center should always be the now position.
5. There will be dots added to the control in real time that represent event that occurred. Clicking the dot will invoke some other action. (Don't need to code that action right now, just the dots appearing)
6. I'd like to provide the option for smooth scrolling or incremental scrolling. This would probably be done using a constant motion for smooth scrolling and for incremental, it would move in response to a timer tic.

using System;
using System.Timers;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication1
{
    public partial class Timeline : UserControl
    {
        Timer timer = null;

        public string CurrentTime
        {
            get { return (string)GetValue(CurrentTimeProperty); }
            set { SetValue(CurrentTimeProperty, value); }
        }

        public static readonly DependencyProperty CurrentTimeProperty =
            DependencyProperty.Register("CurrentTime", typeof(string), typeof(Timeline), new PropertyMetadata(""));

        public Timeline()
        {
            InitializeComponent();

            setup();
        }

        private void setup()
        {
            timer = new Timer();
            timer.Elapsed += timer_Elapsed;
            timer.Interval = 1000;
            timer.Enabled = true;
        }

        private void timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            CurrentTime = DateTime.Now.TimeOfDay.ToString();
        }
    }
}

The calling thread cannot access this object because a different thread owns it.

public List<Person> People = new List<Person>();

People.Add(new Person { Id = 0, Name = "Joe" });
People.Add(new Person { Id = 1, Name = "Pete" });
People.Add(new Person { Id = 2, Name = "Sam" });

System.Windows.Controls.DataGridComboBoxColumn comboCol = new System.Windows.Controls.DataGridComboBoxColumn();
comboCol.Header = "People";
comboCol.ItemsSource = People;
comboCol.DisplayMemberPath = "Name";
comboCol.SelectedValuePath = "Id";
this.taskGrid.Columns.Add(comboCol);