MC-843: Heading live edit should become unfocused on drag action

- Added logic to blur active element on draggable handle click

Author: Hwashiang Yu

app/code/Magento/PageBuilder/view/adminhtml/web/js/binding/draggable.js

@@ -12,6 +12,13 @@ import ko from "knockout";
 // Create a new sortable Knockout binding
 ko.bindingHandlers.draggable = {
     init(element, valueAccessor) {
-        $(element).draggable(valueAccessor());
+        $(element).on("mousedown", () => {
+            try {
+                (document.activeElement as HTMLElement).blur();
+            }
+            catch (error) {
+                console.error(error);
+            }
+        }).draggable(valueAccessor());
     },
 };