The Thumbnail Grid View
Clicking the icon to the right of the navigator panel toggle will switch to thumbnail grid view, shown here.
This view shows thumbnails of all of your wireframes and is useful for getting an overview of your project. It allows you to see more of your wireframes at once and is a good view to use for reordering and tidying up (e.g., renaming and moving to the trash). You can trash multiple wireframes at once by selecting them (using CTRL/SHIFT+ click) and bringing up the context menu.
Thumbnail grid view is available when viewing wireframes and assets, and is the only view available for trash.