[orca-list] Empty paragraphs in Mozilla Thunderbird (message editing)

[Jason White <jason jasonjgw net>]

Mozilla Thunderbird seems to be effective at triggering braille issues.

Steps to reproduce:

1. In the body of a message, insert an empty paragraph (e.g., between 
two paragraphs containing text).

2. Use up/down arrow keys to navigate between the paragraphs.

Expected result: When the editable empty paragraph receives focus, the 
braille display should show a blank line (cursor at cell 1).

Actual result: the braille display shows the text of the previous 
paragraph that had focus.

In debug.out, I notice the following. Would it be possible to process 
the event appropriately in this context without causing regressions 
elsewhere?

vvvvv PROCESS OBJECT EVENT object:text-caret-moved vvvvv
14:48:58.059466 - OBJECT EVENT: object:text-caret-moved (0, 0, 0)
                  app.name='Thunderbird' name='' role='paragraph'
                  states='editable enabled opaque sensitive showing 
visible'
                  relations=''
                  interfaces='Accessible Collection Component 
EditableText Hypertext Hyperlink Text'
                  attributes='formatting:block display:block 
margin-bottom:16px margin-top:16px tag:p margin-right:0px 
text-indent:0px text-align:start margin-left:0px'
14:48:58.060045 - EVENT MANAGER: Getting script for [application | 
Thunderbird] (check: True)
14:48:58.061227 - EVENT MANAGER: Script is 
<orca.scripts.apps.Thunderbird.script.Script object at 0x7f8d40f61940>
14:48:58.061257 - EVENT MANAGER: Change active script: False (The script 
for this event is already active.)
14:48:58.061465 - GECKO: [paragraph | ] is in an editable document: 
[document web | Message body]
14:48:58.062482 - WEB: Context: [paragraph | ], 0 (focus: [paragraph | ])
14:48:58.063106 - WEB: Event ignored: Was for object we're treating as 
textless
14:48:58.063215 - EVENT MANAGER: locusOfFocus: [paragraph | ] 
activeScript: <orca.scripts.apps.Thunderbird.script.Script object at 
0x7f8d40f61940>
14:48:58.063231 - EVENT MANAGER: _lastCommandWasCaretNav: False
14:48:58.063236 - EVENT MANAGER: _lastCommandWasStructNav: False
14:48:58.063240 - EVENT MANAGER: _lastCommandWasMouseButton: False
14:48:58.063244 - EVENT MANAGER: _inFocusMode: True
14:48:58.063248 - EVENT MANAGER: _focusModeIsSticky: False
14:48:58.063252 - EVENT MANAGER: _browseModeIsSticky: False
TOTAL PROCESSING TIME: 0.0038