public Document(Gdk.Size size)
{
Selection = new DocumentSelection ();
Guid = Guid.NewGuid ();
Workspace = new DocumentWorkspace (this);
IsDirty = false;
HasFile = false;
HasBeenSavedInSession = false;
ImageSize = size;
UserLayers = new List<UserLayer>();
tool_layer = CreateLayer ("Tool Layer");
tool_layer.Hidden = true;
selection_layer = CreateLayer ("Selection Layer");
selection_layer.Hidden = true;
ResetSelectionPaths ();
}