说明：  VB ImgCombo带图像的Combo下拉框，给下拉框的各个下拉项前面添加一个小图标，比如本实例中，列出所有盘符，但是在前面会增加一个硬盘的图标，这样更形象一些，提升软件使用体验，通过本源码，你将会学会这种图标的添加方法。 　　注：本源码来自国外，早些年的代码，注释是英文。
(VB imgcombo with image combo drop-down box, add a small icon in front of each drop-down item in the drop-down box. For example, in this example, all drive letters are listed, but a hard disk icon will be added in front of it, which is more vivid and improves the software experience. Through the source code, you will learn how to add this icon. Note: the source code from abroad, earlier years of code, comments are in English.)