DevExpress builds combo boxes in a very odd way. The standard identification built in to Selenuim and Watir (including Page Objects) does not see it as a Select List. So how can you automate these successfully?
So as it turns out, DevExpress builds combo boxes as a text box with several layered tables associated with it but not under the text box in the HTML tree. interactions are all done via embedded scripts.
I found the simplest way to automate this object is to identify the text box and the lowest table containing the list of items (3rd table down).
for example (using Watir and Page Objects)
table(:list,:id => 'ComboBoxValue_DDD_L_LBT')
text_field(:state, :id => 'ComboBoxValue_I') #:name => 'State')
I have not found a way to get better IDs at these levels, but we are working that issue. Then your select code looks like this:
self.state_element.click
row = list_element.find { |row| row[0].text == value }
row.click