By default all active tags are displayed in the Catalog Tags panel. This can be very confusing when viewing the content of more than one tag at the same time. The single-tag mode with only one tag section displayed saves you from unnecessary and time-consuming up and down scrolling to get to the respective areas.
If you move the mouse pointer over any of the tag headings, a small rectangular icon appears at the right edge of each section. After clicking on it,
the other tag headings are hidden and only this one remains visible in the Catalog Tags panel.
You can quit the single tag mode at any time by simply clicking again on the small rectangular icon.
Left-clicking on the tag heading allows you to select from the drop-down menu a different tag category to display.
In this way you can always display only the currently required tag-heading to take advantage of using the entire screen height.