private void SP_ToggleButton_Click(object sender, EventArgs e)
 {
     if (isSliding_PanelExpanded)
     {
     }
     SP_Timer.Start();
 }
 private void SP_Timer_Tick(object sender, EventArgs e)
 {
     if (isSliding_PanelExpanded)
     {
         // retract pannel
         Sliding_Panel.Width -= 22;
         if (Sliding_Panel.Width <= MinSliderWidth)
         {
             //stop retract
             isSliding_PanelExpanded = false;
             SP_Timer.Stop();
             retractSliding_PanelGUI();
             this.Refresh();
         }
     }
     else
     {
         //expand the pannel
         Sliding_Panel.Width += 22;
         if (Sliding_Panel.Width >= MaxSliderWidth)
         {
             //stop expanding
             isSliding_PanelExpanded = true;
             SP_Timer.Stop();
             expandSliding_PanelGUI();
             this.Refresh();
         }
     }
 }