ui: scratchpad: allow close left main pane (#405)

packages/ui-default/components/scratchpad/index.jsx

@@ -97,10 +97,12 @@ export default function ScratchpadContainer() {
       </div>
       <SplitPane
         defaultSize={ui.main.size}
-        minSize={250}
+        size={ui.main.size}
+        minSize={ui.activePage !== null ? 250 : 0}
         split="vertical"
-        primary="second"
+        primary="first"
         onChange={(size) => handleChangeSize('main', size)}
+        allowResize={ui.activePage !== null}
       >
         <div className="scratchpad__problem">
           {Object.keys(pages).map((key) => {

packages/ui-default/components/scratchpad/reducers/ui.ts

@@ -4,6 +4,7 @@ import i18n from 'vj/utils/i18n';
 export default function reducer(state = {
   main: {
     size: '50%',
+    savedSize: '50%',
   },
   pretest: {
     visible: ['default', 'fileio'].includes(UiContext.pdoc.config?.type)
@@ -120,9 +121,22 @@ export default function reducer(state = {
       };
     }
     case 'SCRATCHPAD_SWITCH_TO_PAGE': {
+      let newPage = action.payload;
+      let { size } = state.main;
+      if (newPage === state.activePage) {
+        newPage = null;
+        (size as any) = 0;
+      } else if (state.activePage === null) {
+        size = state.main.savedSize;
+      }
       return {
         ...state,
-        activePage: action.payload,
+        main: {
+          ...state.main,
+          size,
+          savedSize: state.main.size,
+        },
+        activePage: newPage,
       };
     }
     default: