[orca-list] Spread sheet selection not detecting when the selection is lost

[Peter Vágner <pvagner pvagner tk>]

Hello,

Alex has just asked me to look at 
https://bugs.documentfoundation.org/show_bug.cgi?id=100086 and in the 
process I think I have discovered little issue with orca's spread sheet 
selection presentation.

Steps:
* Make sure Always speak selected spread sheet range is not checked
* Open a spread sheet document in libre office
* Move to cell A1
* Press shift+right arrow key twice. Cells B1 and C1 will become 
selected and orca will report to the fact as the selection changes.
* Now press shift+orca+up arrow key to confirm A1 through C1 is selected.
* Now press right arrow key. The selection will be cancelled and orca 
will report cell B1. That's all seemingly good.
* Now press shift+orca+up arrow again to verify nothing is selected.
* Now press shift+right arrow. C1 will become selected as an addition to 
B1 however orca will report A1 unselected as if all three rows A1, B1 
and C1 were still selected in previous step. It should report C1 
selected I would say.

Current:
I think orca reacts to object:selection-changed events and calculates 
which rows and cols are being selected or unselected and reports the 
differences.
Most likelly it newer clears the selection if the cursor is moved 
without manipulating the selection and the selection is lost.

Expected
Orca should be somehow able to detect when the selection is cancelled. I 
am not sure if object:active-descendant-changed event is a good signal 
for that though.


Greetings

Peter