.cs

 public class Attributes_Custom : Grasshopper.Kernel.Attributes.GH_ComponentAttributes {

        //public bool userClick0 =false;
        public Attributes_Custom(GH_Component owner) : base(owner) { }

        protected override void Layout() {
            base.Layout();

            System.Drawing.Rectangle rec0 = GH_Convert.ToRectangle(Bounds);
            rec0.Height += 22;

            System.Drawing.Rectangle rec1 = rec0;
            rec1.Y = rec1.Bottom - 22;
            rec1.Height = 22;
            rec1.Inflate(-2, -2);

            Bounds = rec0;
            ButtonBounds = rec1;
        }
        private System.Drawing.Rectangle ButtonBounds { get; set; }

        protected override void Render(GH_Canvas canvas, System.Drawing.Graphics graphics, GH_CanvasChannel channel) {

            SolverGH baseClass = Owner as SolverGH;

            base.Render(canvas, graphics, channel);

            if (channel == GH_CanvasChannel.Objects) {
                var color = baseClass.userClick0 ? GH_Palette.White : GH_Palette.White;
                GH_Capsule button = GH_Capsule.CreateTextCapsule(ButtonBounds, ButtonBounds, color, baseClass.userClick0.ToString(), 2, 0);
                button.Render(graphics, Selected, Owner.Locked, false);
                button.Dispose();
            }
        }
        public override GH_ObjectResponse RespondToMouseDown(GH_Canvas sender, GH_CanvasMouseEvent e) {

            SolverGH baseClass = Owner as SolverGH;


            if (e.Button == System.Windows.Forms.MouseButtons.Left) {
                System.Drawing.RectangleF rec = ButtonBounds;
                if (rec.Contains(e.CanvasLocation)) {
                    baseClass.userClick0 = !baseClass.userClick0;
                    //MessageBox.Show("The button was clicked", "Button", MessageBoxButtons.OK);
                    baseClass.ExpireSolution(true);
                    return GH_ObjectResponse.Handled;
                }
            }
            return base.RespondToMouseDown(sender, e);
        }
    }