Error in Mandelbrot example

On some machine configurations the Mandelbrot .NET example program will crash with an 'Invalid parameter used' unhandled exception when run.

Line 105 of form1.cs in the MandelbrotFrontend should be changed from

bitmap1 = new Bitmap(255,255); 

to

bitmap1 = new Bitmap(pictureBox1.Height-1, pictureBox1.Width-1);