WPF自制TextBox利用Validation验证来实现必填项和焦点的提示特效。必填项的用户名和Email的提示为，不满足规则不消失，有警示作用。非必填项身份证和QQ号的提示为，无论规则满足与否，提示只与焦点有关，即焦点失去即消失。个人觉得效果很好。-Homemade WPF TextBox Validation validation required prompt and focus effects. Required user name and Email tips, does not s