Fix Clear button not working with custom question

macao/assets/gapfill-select.js

@@ -51,11 +51,25 @@ export const gapfillSelectWidget = {
                     optionElem.innerText = opt;
                     segmentElem.appendChild(optionElem);
                 }
-                // Add listener to update the question's value when the selector's value changes
+                // Add callback to update the question's value when the selector's value changes
                 segmentElem.addEventListener("change", (e) => {
                     // The select node knows its index, therefore is able to update the question value at the correct index
                     question.value[parseInt(e.target.getAttribute("data-index"))] = e.target.value;
                 });
+                // Add callback to update the DOM nodes when the question's value changes
+                question.valueChangedCallback = () => {
+                    const gaps = question.wrapperElement.querySelectorAll("#gapfill-container select");
+                    if (question.value instanceof Array && question.value.length === gaps.length) {
+                        for (const i in question.value) {
+                            gaps[i].value = question.value[i];
+                        }
+                    } else {
+                        // Unknown value -> reset all fields
+                        for (const gap of gaps) {
+                            gap.value = undefined;
+                        }
+                    }
+                }
                 nbGaps++;
             }
             // Add segment