There are five toggles on the Status bar that switch features on and off:
Show Grid: When enabled, a visible grid is overlayed on PDFs in the main workspace.
Snap To:
Grid: When enabled, any points used to define a markup line up are forced to line up with the grid (even if the grid is not currently visible).
Content: When enabled, markups automatically snap to the underlying PDF vector content. Snap to Content does not snap to text or images in the PDF, only vector images such as lines and shapes.
Markup: When enabled, markups automatically snaps to other markups in the PDF. Two related behaviors will occur: the cursor will snap to points on other markups (similar to how Snap to Content snaps to points in the PDF content) and Revu will also show—and the cursor will snap to—guidelines that are based on lines in nearby markups.
Snap to a point
Guidelines creating a Polygon
Guideline creating aligned Rectangles
Reuse: When enabled, after placing a markup, the same markup can be added to the PDF without having to reselect it. This mode is helpful when adding the same markup onto the PDF sequentially.
Sync: When enabled, Revu synchronizes the viewing windows when displaying PDFs in side-by-side Split View mode or in a detached window. This is useful when you need to compare two different versions of the same document. Moving the document in one window will automatically adjust the view in the second window.