If a WiringUI.apply() includes the instantiation of an SHtml.ajaxText object, the resulting ajaxText's call-back function is not registered in the function table. The result is that ajax call-backs of the text element will not cause the function to execute.

When discussed on the mailing list (see link below) dpp specifically said that this is because "the postPageJavaScript list is executed after the function table is loaded into the session, rather than before".

more information
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liftweb group discussion: https://groups.google.com/group/liftweb/browse_thread/thread/a136b761470aa277
repro: https://github.com/davewhat/WiringUI-and-ajaxText-trouble