Created attachment 156283 [details]
LibreOffice Writer document which shows the problem.

Bug: Area color fills the space between two paragraphs!


To reproduce:

1. Open a new writer document.

2. Open the "Styles and Formatting" side panel:
   "View" > "Styles".

3. In the "Styles and Formatting" side panel:
   3.1 Select "Show previews".
   3.2 Select "Custom Styles" category from the list.

4. In the "Styles and Formatting" side panel:
   4.1 Create a new paragraph style with the following options:
       Organizer tab
         "Style Name": MyParagraph2
         "Style Next style": MyParagraph2
         "Style Inherit from": -None-
         "Style Category": Cusom Styles
       Indents & Spacing tab
         "Spacing Above paragraph": 0.20 "
       Borders tab
         "Line Arrangement Presets": Set All Four Borders
         "Properties": turn on "Merge with next paragraph"

5. In the "Styles and Formatting" side panel:
   5.1 Create a new paragraph style with the following options:
       Organizer tab
         "Style Name": MyParagraph3
         "Style Next style": MyParagraph3
         "Style Inherit from": -None-
         "Style Category": Cusom Styles
       Indents & Spacing tab
         "Spacing Above paragraph": 0.20 "
       Borders tab
         "Line Arrangement Presets": Set All Four Borders
         "Properties": turn on "Merge with next paragraph"

6. With the cursor in the document type:
     "Line1" <Enter> <Enter>
     "Line2" <Enter> <Enter>
     "Line3" <Enter> <Enter>

   so the results look like:
     Line1
     <blank_line>
     Line2
     <blank_line>
     Line3
     <blank_line>
     <blank_line>

7. Apply the "MyParagraph2" paragraph style to "Line2".
   Apply the "MyParagraph3" paragraph style to "Line3".

8. Test #1 - Delete the empty paragraph between "Line2" and "Line3".
   Result: Pass
   Outcome: The "Line2" paragraph merges with the "line3" paragraph and the border surrounds both paragraphs.
   Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.

9. Edit the "MyParagraph2" paragraph style and:
   uncheck, "Borders" tab > "Properties" > "Merge with next paragraph" option.

10. Test #2 - Delete the empty paragraph between "Line2" and "Line3".
    Result: Pass
    Outcome: The "Line2" paragraph does not merge with the "line3" paragraph and each paragraph has its own border.
    Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.

11. Edit the "MyParagraph2" paragraph style and:
    check, "Borders" tab > "Properties" > "Merge with next paragraph" option.
    select, "Area tab" > "Color" > "Light Gray 5".

12. Test #3 - Delete the empty paragraph between "Line1" and "Line2".
    Result: Pass
    Outcome: The "Line2" paragraph merges with the "line3" paragraph, the border surrounds both paragraphs, and only the "Line2" paragraph has area color.
    Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.

13. Edit the "MyParagraph2" paragraph style and:
    uncheck, "Borders" tab > "Properties" > "Merge with next paragraph" option.

14. Test #4 - Delete the empty paragraph between "Line2" and "Line3".
    Result: Pass
    Outcome: The "Line2" paragraph does not merge with the "line3" paragraph, each paragraph has its own border, and only the "Line 2 paragraph has area color.
    Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.

15. Edit the "MyParagraph2" paragraph style and:
    check, "Borders" tab > "Properties" > "Merge with next paragraph" option.

16. Edit the "MyParagraph3" paragraph style and:
    select, "Area tab" > "Color" > "Light Gray 5".

17. Test #5 - Delete the empty paragraph between "Line1" and "Line2".
    Result: Pass
    Outcome: The "Line2" paragraph merges with the "line3" paragraph, the border surrounds both paragraphs, and both the "Line2" and "Line3" paragraphs have area color.
    Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.

18. Edit the "MyParagraph2" paragraph style and:
    uncheck, "Borders" tab > "Properties" > "Merge with next paragraph" option.

19.Test #6 - Delete the empty paragraph between "Line2" and "Line3".
   Result: Fail
   Outcome: The "Line2" paragraph does not merge with the "line3" paragraph, each paragraph has its own border, each paragraph has area color, but now area color fills the space between the two paragraphs! (Note: This only happens if the two paragraphs have the exact same area color.)
   Finish the test, by pressing 'Ctl+z' to undo the paragraph deletion.