Manual test for Caret Browsing. Resize your window until the first paragraph fills at least two lines of text . Enable caret browsing mode (usually by pressing theF7 key). Press down. Now you should be on the second line of the first paragraph. Press up. Now you should be on the first line again. Now press Ctrl+Down.
You should be on the first line of the second paragraph now. Press Ctrl+Down again.
You should be on the first line of the third paragraph now. Press Ctrl+Up, and you should be back on the second paragraph.