Structure widget is displayed in a separate tab on the project page if the project is enabled for Structure.
The widget on the project page is the standard, fully-functional Structure widget and has the same functionality you can find on the Structure Board (except for Perspectives and Issue Details panel), but it has several specific features not found on the Structure Board.
The current project defines the scope of the displayed data – it's used to filter the structure and show project issues in the second panel.
Layout
When you open Structure tab, Double Grid layout is selected automatically.
The primary (left) panel displays the most recently viewed structure or the default structure for the current project (as defined in the Options dialog). You can quickly switch to another structure by clicking the structure name and selecting the desired structure.
The secondary (right) panel shows issues from the current project that are not part of the selected structure. This allows to quickly place other issues in the project into the structure.
Automatic Filter
An automatic project filter is added to the primary panel. This is a non-removable transformation that hides all issues from other projects.
If you'd like to see the full structure without this filter, click Open link in the Structure widget's footer.
Project Page Options
You can make the widget open with the structure that is defined as a default structure for this specific project.
To do that, click the options gear button in the top right corner and select the Auto-switch option. The changes are saved to the server and applied immediately.
If you are the Project Administrator, the options dialog will also show the link to a page where you can change the default structure for your project.
The default value for this option can be configured by JIRA Administrator on the Structure Defaults page.