You can open a single thumbnail by clicking View, or multiple ones by putting a checkmark in the thumbnail and clicking the Open icon
The selected plan pages will appear as tabs and be clicked on for quick navigation.
TIP: You can select multiple thumbnails at one time. Press Shift on your keyboard and put a checkmark in the corner of the first plan. Then click in the center of the last plan (click View, instead of putting a checkmark in the corner). This will select all the plans in-between.