[orca-list] table navigation commands and empty cells in Firefox

[Zahari Yurukov <zahari yurukov gmail com>]

Hi,
I'm experiancing this for at least a few months, but I'm almost sure
someone reported it in the past, at least that's the reason I didn't
reported it myself. Now I'm not so sure, may be I've missed something,
so sorry if that's actually a Firefox bug or something.
So if you have a table with empty cells, like on:
https://en.wikipedia.org/wiki/List_of_screen_readers

and you enter the table, and then use the table navigation commands,
when you land on empty cell, Orca gets confused.
For example, let's get the first table, one with 60 rows and 5 cols,
where the last column is "Notes", and not every row has content in that
column. So we load the page, press t, and we're on the first row first
column. I already know that the 4th row doesn't have a "Notes" column,
so lets get to it pressing Alt+Shift+downArrow 3 times - Orca reads
"BrowseAloud", which is correct.
Now if I press repeatedly Alt+Shift+rightArrow, Orca reads the contents
of column 2, column 3, etc, but when I get to the last column 5 (that
one empty column with "Notes"), the next press of Alt+Shift+rightArrow
places me on row 5, column 2. In fact, as soon as I step on row 4 column
5, Orca thinks I'm on row 5 column1.

I'm using Firefox 39.0 with the latest Orca from master (commit
e3a36915da5589c9c96346889feee370d5c3add5).

Best wishes,
Zahari