ui: fix #1131

packages/components/frontend/autocomplete/AutoComplete.tsx

@@ -266,7 +266,7 @@ const AutoComplete = forwardRef(function Impl<T>(props: AutoCompleteProps<T>, re
         className={focused ? 'autocomplete-wrapper focused' : 'autocomplete-wrapper'}
         style={{ width, height }}
       >
-        <DndProvider backend={HTML5Backend}>
+        <DndProvider backend={HTML5Backend} context={window}>
           {multi && selectedKeys.map((key) => {
             const item = valueCache[key];
             return (

packages/ui-default/components/problemconfig/ProblemConfigTree.tsx

@@ -146,7 +146,7 @@ export function SubtaskConfigTree() {
 
 export function ProblemConfigTree() {
   return (
-    <DndProvider backend={HTML5Backend}>
+    <DndProvider backend={HTML5Backend} context={window}>
       <div className="row">
         <div className="medium-6 columns">
           <SubtaskConfigTree />