So if you can't commit your local changes yet, you have to put them aside while you're working on the urgent issue. The shelving feature helps you do exactly that: you can store your local changes on a shelve, get your working copy in a clean state again and work on the issue. After you're finished with the urgent issue and you've committed those changes, you can unshelve your shelved work and continue working on your previous task again.
To shelve your local changes, select your working copy and use→ The following dialog allows you to select the files you want to shelve and give a name under which you want to store them.
If you select an existing shelf, then a new version is created for that shelf. If you provide a new name, a new shelf is created for the selected files.
使用→ 打开unshelve对话框来unshelve更改。这个对话框列出了所有shelved的项目。选择你想要的shelved 项目和回退到你工作副本的版本，然后单击
That means that while shelving works as advertised, it is still in a stage where it's heavily improved and worked on. That also means that there's no guarantee that the shelves you create are upwards compatible and future versions might not be able to use them. And of course the UI might change as well in future versions to accommodate new features and behaviors.