drop down menu - dojo comboBox automatically trigger dropdown -

i using combobox , reason automaticall triger dropdown menu appear when have results not working. there way trigger dynamically. maybe onchange event?

i using dojo 1.6!

a code example nice can recommend alternatives or better solutions, in case want open dropdown programmatically, should find opendropdown() , toggledropdown() functions on combobox object. if have dojo source can find more dropdown related functions in dijit/_hasdropdown.js, combo box inherits from.