参考:http://wenku.baidu.com/link?url=BT2U6Z-HktQJQYpz3Jp88pJSp4lU-lXkvCqpdeaa9a-BVdOgMGK1vj486-32YC4GqufG8_IV7TmTR213LJQOcuZo68fgdrNWExcCwthOcXO
在Window>preference>Spket>JavaScript Profiles>ExtJS(新建)>ExtJS(选择)>添加file选择ext_debug.js/ext_all_dev.js文件;
选择之后重新启动MyEclipse;