Automating an ExtJS web application can be difficult due to the dynamic nature
of the page. For example, the majority of unique ID attributes in the HTML will
be different between builds, which causes problems locating elements reliably.
Another issue is selected items from a ComboBox, which is not a normal HTML
<select> element, but an <input> that is populated from data in a completely
separate section of the DOM.
Below is a solution for locating the ComboBox elements and the Selenium commands
needed to select values in them. This example is taken from code written for the
Selenium RC Java client library.