C#

public sealed class DB
{
  private static SqlConnection connection;
  private static object syncRoot = new object();
  public static SqlConnection Connection
  {
    get
    {
      if (connection == null)
        lock (syncRoot)
          if (connection == null)
            connection = new SqlConnection(
              ConfigurationSettings.AppSettings["ConnectionString"]);
      return connection;
    }
  }
}

if (myControl.IsHandleCreated)
{
    // Do whatever you're gonna do by invoking
}
else
{
    // Do the same thing, but on the current thread
    // instead of using invoke
}

if (IsHandleCreated)
{
  SendMessage(Handle, SOME_MESSAGE, 0, value); // Just making stuff up
  fieldSet = true;
}
else
{
  fieldSet = false;
}
fieldName = value;

if (!fieldSet)
  SendMessage(Handle, SOME_MESSAGE, 0, fieldName);