1、图形元素绘制（线：绘制、移动，拉伸、清除等），双缓存。 2、进程：创建、停止、列表 3、普通控件使用。-1, graphics, drawing elements (lines: map, move, stretch, clear, etc.), double-buffering. 2, process: create, stop, list 3, the use of common control.

Query Builder is a custom web control which allows the user to build a query and verify/execute it. The web control lists all of the layers that are available on the primary map resource. When a user selects a layer, the query automatically populates