switch to using microtasks for switching, fixing segfaults

src/DirectoryView.cpp

@@ -4,12 +4,15 @@
 DirectoryView::~DirectoryView() {}
 
 void DirectoryView::update() {
-    window()->start_batch();
+    // microtasks defer execution of the callback until all external events are processed.
+    // if they're not used here and update() is called in a click or hover handler,
+    // chaos will ensue, as the widget tree will be updated during event propagation
+    window()->queue_microtask([this]() {
         target()->clear_children();
         for (const auto &entry : std::filesystem::directory_iterator(m_current_path)) {
             auto button = m_target->add<FileButton>(entry.path().filename(), this);
         }
-    window()->end_batch();
+    });
 }
 
 void DirectoryView::navigate(std::string path) {