firefox3支持旧版本插件

1. 打开 about:config
2. 右键点击页面，New->Boolean，名称为 extensions.checkCompatibility 值为 false
3. 右键点击页面，New->Boolean，名称为 extensions.checkUpdateSecurity 值为 false
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use old version plugin for firefox 3

1, open about:config
2, right click, new-boolean, name: extensions.checkCompatibility and value is false
3, right click, new-boolean, name: extensions.checkUpdateSecurity and value is false

Done!