Description:
Suppose we want to animate a textbox by nth level paragraphs during slideshow. 
Let us assume that this textbox has 5 lines at the beginning.
When we set animation, all 5 lines appear in the Animation control panel at right.

And here's the bug: This definition is NOT dynamically linked with the actual textbox. If we edit the textbox to add or delete lines, this definition does not change. So the slideshow fails to animate the textbox in a weird way.

For example, if I add more lines to the textbox after setting the animation, these additional lines will not be animated: They will appear on the screen as soon as the slide comes up. This spoils the entire slideshow!

A more nuanced case is when I delete a line and then insert another line in its place. For me, this is equivalent to "replacing" that old line. But Impress treats this line as a completely new line, and won't animate it.

The solution is to define the animation DYNAMICALLY: Impress should animate the latest version of the textbox.

Another way to look at this is to tell Impress is to look at the textbox as an object that has to be animated by nth level paragraph. It does not have to remember the lines by heart. It must take the latest version of the textbox and animate it.

Steps to Reproduce:
1.Create a textbox with any number of lines.
2.Set animation by nth level paragraphs (the exact level does not matter here). 
3. Check animation by pressing SHFT+F5.
4. Add a line in the textbox. 
5. Now check animation again by pressing SHFT+F5.
The newly added line will not be animated. [BUG]

6. Delete a line and insert another line in its place.
7. Now check animation again by pressing SHFT+F5.
The newly replaced line will not be animated. [BUG]

Actual Results:
See above

Expected Results:
See above


Reproducible: Always


User Profile Reset: No



Additional Info:
[Information automatically included from LibreOffice]
Locale: en-US
Module: Impress
[Information guessed from browser]
OS: Windows 10 Home, 64 bits