我确定这是一个重复的问题，但我找不到答案相同的问题.

I'm sure this is a duplicate, but I can't find a question with the same answer.

将 Horizo​​ntalContentAlignment="Stretch" 添加到您的列表框.这应该够了吧.请小心使用自动完成功能，因为很容易错误地获取 Horizo​​ntalAlignment.

Add HorizontalContentAlignment="Stretch" to your ListBox. That should do the trick. Just be careful with auto-complete because it is so easy to get HorizontalAlignment by mistake.