Language direction on table is <not set> when LTR icon is clicked

[James]

Steps to reproduce:

1. Open the Ajax sample.
2. Click on the Insert table icon.
3. Click on the Advanced tab and select "Left to Right (LTR)" from the language direction combo box & click OK.
4. See that a table is created with language direction set to LTR.
5. Press CTRL + A to select the entire table & click on the RTL icon.
6. See that the table now has language direction set to RTL.
7. Press CTRL + A to select the entire table & click on the LTR icon.
8. Right click on the table & select Table Properties from the context menu.
9. Click on the Advanced tab and check the value in the language direction combo box.

Expected: The value in the combo box is Left to Right (LTR).

Actual: The value in the combo box is <not set>.

[Krzysztof Studnik]

Confirmed since 3.4

[Garry Yao]

The dialog field reflects explicit text direction instead of computed style.