用法：
//使用颜色作为背景
String pressed = "#333333";
String selected = "#333333";
String normal = "#888888";
Object b = i.nuibs(pressed, selected, normal);

//使用图像作为背景
String pressed = "%a.png";
String selected = "%a.png";
String normal = "%b.png";
Object b = i.nuibs(pressed, selected, normal);

//使用渐变颜色作为背景
.配置选中状态背景
int a = 0;
int b = 0;
String c = "#255779|#3e7492|#a6c0cd";
String d = "0";
String e = "topbottom";
Object pressed = i.ngde(a, b, c, d, e);

.配置正常状态背景
int a = 0;
int b = 0;
String c = "#255779|#3e7492|#a6c0cd";
int d = "0";
String e = "rightleft";
Object normal = i.ngde(a, b, c, d, e);

Object selected = pressed;

Object b = i.nuibs(pressed, selected, normal);

说明：
输入按下背景，输入选中背景，正常状态背景。