One way is to make a hidden textbox populate with the value that the control isn't sending.
Can set the hidden textbox when the controls value is changed or before the run button runs the report.
This would be the javascript could use that would get the DisplayValue/text of the control and set that value to another control.
IbComposer_setCurrentSelection('txtDDLDescription',IbComposer_getCurrentSelectionEx('cbxDDLValue')[0].getDisplayValue(), false);
cbxDDLValue would be the name of the control that want both the value and display value for. While the txtDDLDescription is the new hidden control that can link the second parameter to.
If want to reverse so the hidden control has the value can do .getValue() instead of .getDisplayValue()
Those are functions IBI made and at least according to the documentation should be in 8.1.5m. This is a link to where can learn about those functions.
Using JavaScript Code With HTML Canvas Pages
WF: 8201, OS: Windows, Output: HTML, PDF, Excel