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The calling thread cannot access this object because a different thread owns it
drawThread = new Thread(new ThreadStart(drawPosters));
                drawThread.SetApartmentState(ApartmentState.STA);
                drawThread.Start();

while (true)
{
  waitEvent.WaitOne();
  //do some calculations
  // change uniform grid rows & cols
  posterUniformGrid.Rows = calculatedRows; //**-> error is first thrown here**
  posterUniformGird.Columns = calculatedCols;
}

Dispatcher.Invoke(DispatcherPriority.Normal,
                    new Action<object[]>(SetGrid),
                    new object[] { calculatedRows, calculatedColumns });

while (true)
 {
   waitEvent.WaitOne();
   this.InvokeEx(t => t.posterUniformGrid.Rows = calculatedRows);
   this.InvokeEx(t => t.posterUniformGird.Columns = calculatedCols);
 }

 public static class ISynchronizeInvokeExtensions
    {
        public static void InvokeEx<T>(this T @this, Action<T> action) where T : ISynchronizeInvoke
        {
            if (@this.InvokeRequired)
            {
                try
                {
                    @this.Invoke(action, new object[] { @this });
                }
                catch { }
            }
            else
            {
                action(@this);
            }
        }
    }