void baseElement_MouseEnter(BaseElement sender, MouseEventArgs e)
 {
     if (!tooltip)
     {
         tooltip = ItemTooltip.Create(this);
         tooltip.Destroyed += tooltip_Destroyed;
     }
 }
 void itemElement_MouseLeave(BaseElement sender, MouseEventArgs e)
 {
     if (tooltip)
         Destroy(tooltip.gameObject);
 }