fix: allow manual virtual tree scrolling

sidebar-controller.js

@@ -155,7 +155,7 @@
       return state.searchQuery && state.searchExpandedKeys ? state.searchExpandedKeys : state.expandedKeys;
     }
 
-    function commit() {
+    function commit(options = {}) {
       const rows = treeApi.flattenVisibleRows(model, {
         expandedKeys: effectiveExpandedKeys(),
         selectedKey: state.selectedKey,
@@ -163,10 +163,11 @@
       });
       const activeIndex = rows.findIndex((row) => row.key === state.activeKey);
       const maximumScrollTop = Math.max(0, (rows.length * rowHeight) - state.viewportHeight);
-      if (state.scrollTop > maximumScrollTop) {
-        state = Object.assign({}, state, { scrollTop: maximumScrollTop });
+      const clampedScrollTop = Math.max(0, Math.min(state.scrollTop, maximumScrollTop));
+      if (clampedScrollTop !== state.scrollTop) {
+        state = Object.assign({}, state, { scrollTop: clampedScrollTop });
       }
-      if (activeIndex >= 0 && state.viewportHeight > 0) {
+      if (options.ensureActive === true && activeIndex >= 0 && state.viewportHeight > 0) {
         const activeTop = activeIndex * rowHeight;
         const activeBottom = activeTop + rowHeight;
         let scrollTop = state.scrollTop;
@@ -192,7 +193,8 @@
       const next = reduceSidebar(state, safeAction, visibleRows);
       if (next === state) return lastSnapshot;
       state = next;
-      return commit();
+      const ensureActive = safeAction.type === 'KEY' || safeAction.type === 'SET_ACTIVE';
+      return commit({ ensureActive });
     }
 
     async function search(query) {