public Task StartAsync()
{
//System.Diagnostics.Debugger.Break();
//create a form
form = new System.Windows.Forms.Form();
form.Size = new System.Drawing.Size(500, 500);
//create a viewer object
viewer = new GViewer();
viewer.Dock = System.Windows.Forms.DockStyle.Fill;
viewer.AutoScroll = false;
//viewer.CurrentLayoutMethod = LayoutMethod.MDS;
// control
var b = CreateCommandButton();
form.Controls.Add(b);
b.BringToFront();
viewer.ObjectUnderMouseCursorChanged += new EventHandler<Microsoft.Msagl.Drawing.ObjectUnderMouseCursorChangedEventArgs>(viewer_ObjectUnderMouseCursorChanged);
viewer.MouseDown += new MouseEventHandler(viewer_MouseDown);
viewer.SuspendLayout();
form.SuspendLayout();
form.Controls.Add(viewer as Control);
viewer.ResumeLayout(false);
form.ResumeLayout(false);
viewer.Graph = graph;
return Task.Run(() => form.ShowDialog());
}