In OOo it is a drop-downlist "text direction" in the tab "page" of the
page-style. Why do you need buttons?

The dropdown list is only visible if 'Complex Text Layout' is activated in
'Setup/Language'. Additionally the dropdown list allows only left > right and
right >left. If you activate additionally 'use asian language' you get right >
left (vertikal). 

Left > right (vertikal) as proposed is missing.

Both language settings are deactivated by default here in germany

Most users never would see the possibility to change writimg direction, would
never be aware that changing writing direction is possible in OOWriter. IMHO the
Lotus Smartsuite Solution (4 buttons in page setup, accessible by default,
independendly from language settings) is more user friendly. Changing writing
direction for everybody would allow more complex documents (e.g. for brochueres,
flyers).

Another soulution could be that writing in frames allows to set writing direction.

Naturally I don't insist on 'Buttons'. The dropdown list for everybody and
additionally equipped with left >right (vertikal) would be sufficient too.

according to 
http://qa.openoffice.org/issue_handling/workflowcharts/RFE_issues_by_QA.sxd I 
reassign this issue to requirements and set the status to new

Bugs in text direction support:

1.No User Interface to format the text direction of paragraph.  I can only find
Format -> Page which does it for the entire page.  Please refer to attachment
for an example.
2.Alignment (Left, Right and Centre) doesn't work properly for vertical text. 
The alignment is on a horizontal basis.

Created attachment 45994 [details]
Demonstration of text direction

following release status meeting -> target 3.x