diff --git a/library.json b/library.json
index 6178106e..5e2a1b97 100644
--- a/library.json
+++ b/library.json
@@ -20,7 +20,7 @@
   "dependencies": [
     {
       "name": "RB3201-RBProtocol",
-      "version": "https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip"
+      "version": "https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip"
     }
   ],
   "build": {
diff --git a/platformio.ini b/platformio.ini
index 2b12d4b6..09f3d6e8 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -16,4 +16,4 @@ framework = arduino
 upload_speed = 921600
 monitor_speed = 115200
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/src/builder/widget.h b/src/builder/widget.h
index cacac963..d6045f27 100644
--- a/src/builder/widget.h
+++ b/src/builder/widget.h
@@ -50,15 +50,8 @@ class BuilderMixin {
 
 protected:
     void addCallback(const std::string& name, callback_t cb) {
-        auto& all = self().m_state.callbacks();
-
-        auto old = all.find(name);
-        if (old != all.end()) {
-            delete static_cast<callback_t*>(old->second);
-        }
-
-        auto* cbHeap = new callback_t(cb);
-        all[name] = static_cast<void*>(cbHeap); // fuj
+        auto* cbHeap = static_cast<void*>(new callback_t(cb)); // fuj
+        self().m_state.addCallback(&callbackTrampoline, &callbackDeleter, name, cbHeap);
     }
 
 private:
@@ -69,6 +62,11 @@ class BuilderMixin {
         Constructed w(state);
         (*static_cast<callback_t*>(cb))(w);
     }
+
+    static void callbackDeleter(void *cb) {
+        auto *cb_typed = static_cast<callback_t*>(cb);
+        delete cb_typed;
+    }
 };
 
 class Widget {
diff --git a/src/gridui.cpp b/src/gridui.cpp
index 923e4187..01de3c07 100644
--- a/src/gridui.cpp
+++ b/src/gridui.cpp
@@ -21,6 +21,9 @@ static void defaultOnPacketReceived(const std::string& cmd, rbjson::Object* pkt)
 
 _GridUi::_GridUi()
     : m_protocol(nullptr)
+    , m_protocol_ours(false)
+    , m_update_timer(nullptr)
+    , m_web_server_task(nullptr)
     , m_state_mustarrive_id(UINT32_MAX)
     , m_states_modified(false) {
 }
@@ -36,6 +39,7 @@ void _GridUi::begin(rb::Protocol* protocol, int cols, int rows, bool enableSplit
     }
 
     m_protocol = protocol;
+    m_protocol_ours = false;
 
     m_layout.reset(new rbjson::Object);
     m_layout->set("cols", cols);
@@ -44,15 +48,18 @@ void _GridUi::begin(rb::Protocol* protocol, int cols, int rows, bool enableSplit
 }
 
 rb::Protocol* _GridUi::begin(const char* owner, const char* deviceName) {
-    auto protocol = new rb::Protocol(owner, deviceName, "Compiled at " __DATE__ " " __TIME__, defaultOnPacketReceived);
+    // Start serving the web page
+    m_web_server_task = rb_web_start(80);
+    if(m_web_server_task == NULL) {
+        ESP_LOGE("GridUI", "failed to call rb_web_start");
+        return nullptr;
+    }
 
+    auto protocol = new rb::Protocol(owner, deviceName, "Compiled at " __DATE__ " " __TIME__, defaultOnPacketReceived);
     protocol->start();
 
-    // Start serving the web page
-    rb_web_start(80);
-
     begin(protocol);
-
+    m_protocol_ours = true;
     return protocol;
 }
 
@@ -79,6 +86,45 @@ uint16_t _GridUi::generateUuidLocked() const {
     }
 }
 
+void _GridUi::end() {
+    auto *protocol = m_protocol.load();
+    if(!protocol) {
+        ESP_LOGE("GridUI", "end() called when not initialized!");
+        return;
+    }
+
+    if(m_protocol_ours) {
+        protocol->stop();
+        delete protocol;
+    }
+    m_protocol = nullptr;
+
+    if(m_update_timer) {
+        esp_timer_stop(m_update_timer);
+        esp_timer_delete(m_update_timer);
+        m_update_timer = nullptr;
+    }
+
+    if(m_web_server_task) {
+        rb_web_stop(m_web_server_task);
+        m_web_server_task = nullptr;
+    }
+
+    {
+        std::lock_guard<std::mutex> guard(m_states_mu);
+        m_states.clear();
+        m_states.shrink_to_fit();
+        m_widgets.clear();
+        m_widgets.shrink_to_fit();
+    }
+
+    m_layout.reset();
+    m_state_mustarrive_id = 0;
+    m_states_modified = false;
+    m_tab_changed = false;
+    m_tab = 0;
+}
+
 void _GridUi::commit() {
     std::lock_guard<std::mutex> l(m_states_mu);
     if (!m_layout) {
@@ -124,9 +170,9 @@ void _GridUi::commit() {
         .skip_unhandled_events = false,
 #endif
     };
-    esp_timer_handle_t timer;
-    esp_timer_create(&args, &timer);
-    esp_timer_start_periodic(timer, 50 * 1000);
+
+    esp_timer_create(&args, &m_update_timer);
+    esp_timer_start_periodic(m_update_timer, 50 * 1000);
 }
 
 bool _GridUi::handleRbPacket(const std::string& cmd, rbjson::Object* pkt) {
@@ -181,7 +227,7 @@ void _GridUi::stateChangeTask(void* selfVoid) {
     if (self->m_states_modified.exchange(false)) {
         std::unique_ptr<rbjson::Object> pkt(new rbjson::Object);
         {
-            std::lock_guard<std::mutex>(self->m_states_mu);
+            std::lock_guard<std::mutex> guard(self->m_states_mu);
             char buf[6];
             std::unique_ptr<rbjson::Object> state(new rbjson::Object);
 
diff --git a/src/gridui.h b/src/gridui.h
index 1d3fdf88..323cad23 100644
--- a/src/gridui.h
+++ b/src/gridui.h
@@ -7,6 +7,8 @@
 #include <freertos/FreeRTOS.h>
 #include <freertos/timers.h>
 
+#include "esp_timer.h"
+
 #include "builder/arm.h"
 #include "builder/bar.h"
 #include "builder/button.h"
@@ -68,6 +70,9 @@ class _GridUi {
 
     void commit();
 
+    // Deinitializes GridUi. Frees the protocol, if it was created by GridUI and not by the app.
+    void end();
+
     bool handleRbPacket(const std::string& command, rbjson::Object* pkt);
 
     rb::Protocol* protocol() const { return m_protocol.load(); }
@@ -148,8 +153,8 @@ class _GridUi {
         if (!checkUuidFreeLocked(uuid))
             uuid = generateUuidLocked();
 
-        auto* state = new WidgetState(uuid, x, y, w, h, tab, &T::callbackTrampoline);
-        m_states.push_back(std::unique_ptr<WidgetState>(state));
+        auto* state = new WidgetState(uuid, x, y, w, h, tab);
+        m_states.emplace_back(std::unique_ptr<WidgetState>(state));
 
         auto* widget = new T(T::name(), *state);
         m_widgets.push_back(std::unique_ptr<T>(widget));
@@ -181,7 +186,11 @@ class _GridUi {
     std::vector<std::unique_ptr<WidgetState>> m_states;
 
     std::atomic<rb::Protocol*> m_protocol;
+    bool m_protocol_ours;
+
     std::unique_ptr<rbjson::Object> m_layout;
+    esp_timer_handle_t m_update_timer;
+    TaskHandle_t m_web_server_task;
 
     mutable std::mutex m_states_mu;
     uint32_t m_state_mustarrive_id;
diff --git a/src/widgets/widget.cpp b/src/widgets/widget.cpp
index 7deb8c89..74f3de0c 100644
--- a/src/widgets/widget.cpp
+++ b/src/widgets/widget.cpp
@@ -6,11 +6,12 @@
 
 namespace gridui {
 
-WidgetState Widget::emptyState(0, 0, 0, 0, 0, 0, [](void* cb, WidgetState* state) {});
+std::mutex WidgetState::m_mutex;
 
-WidgetState::WidgetState(uint16_t uuid, float x, float y, float w, float h, uint16_t tab, cb_trampoline_t cb_trampoline)
-    : m_cb_trampoline(cb_trampoline)
-    , m_uuid(uuid)
+WidgetState Widget::emptyState(0, 0, 0, 0, 0, 0);
+
+WidgetState::WidgetState(uint16_t uuid, float x, float y, float w, float h, uint16_t tab)
+    : m_uuid(uuid)
     , m_bloom_global(0)
     , m_bloom_tick(0) {
 
diff --git a/src/widgets/widget.h b/src/widgets/widget.h
index fe6d19df..3ff37076 100644
--- a/src/widgets/widget.h
+++ b/src/widgets/widget.h
@@ -18,6 +18,48 @@ template <typename Self, typename Finished>
 class BuilderMixin;
 };
 
+class WidgetState;
+
+class CallbacksHolder {
+    friend class WidgetState;
+public:
+    typedef void (*cb_trampoline_t)(void*, WidgetState*);
+    typedef void (*cb_deleter_t)(void*);
+
+    ~CallbacksHolder() {
+        for(const auto& itr : m_callbacks) {
+            m_cb_deleter(itr.second);
+        }
+    }
+
+    void call(WidgetState* state, const std::string& event) {
+        auto itr = m_callbacks.find(event);
+        if (itr != m_callbacks.end()) {
+            (*m_cb_trampoline)(itr->second, state);
+        }
+    }
+
+    void add(const std::string& event, void *cb) {
+        auto itr = m_callbacks.find(event);
+        if(itr != m_callbacks.end()) {
+            m_cb_deleter(cb);
+            itr->second = cb;
+        } else {
+            m_callbacks[event] = cb;
+        }
+    }
+
+private:
+    CallbacksHolder(cb_trampoline_t trampoline, cb_deleter_t deleter) : m_cb_trampoline(trampoline), m_cb_deleter(deleter) { }
+
+    CallbacksHolder(const WidgetState&) = delete;
+    CallbacksHolder& operator=(const WidgetState&) = delete;
+
+    std::map<std::string, void*> m_callbacks;
+    const cb_trampoline_t m_cb_trampoline;
+    const cb_deleter_t m_cb_deleter;
+};
+
 /**
  *  @defgroup widgets_constructed Layout widgets
  *  Classes in this module are used to modify state of the already constructed Layout.
@@ -30,10 +72,8 @@ class WidgetState {
     template <typename Self, typename Finished>
     friend class builder::BuilderMixin;
 
-    typedef void (*cb_trampoline_t)(void*, WidgetState*);
-
 public:
-    WidgetState(uint16_t uuid, float x, float y, float w, float h, uint16_t tab, cb_trampoline_t cb_trampoline);
+    WidgetState(uint16_t uuid, float x, float y, float w, float h, uint16_t tab);
 
     uint16_t uuid() const { return m_uuid; }
     const rbjson::Object& data() const { return m_data; }
@@ -45,6 +85,9 @@ class WidgetState {
     void markChanged(const std::string& key);
 
 private:
+    // Each mutex is ~100 bytes of heap allocation. Let's keep just one for this.
+    static std::mutex m_mutex;
+
     WidgetState(const WidgetState&) = delete;
     WidgetState& operator=(const WidgetState&) = delete;
 
@@ -59,20 +102,17 @@ class WidgetState {
         m_mutex.unlock();
     }
 
-    std::map<std::string, void*>& callbacks() {
-        if (!m_callbacks) {
-            m_callbacks.reset(new std::map<std::string, void*>);
+    void addCallback(CallbacksHolder::cb_trampoline_t trampoline, CallbacksHolder::cb_deleter_t deleter, const std::string& event, void *cb) {
+        if (!m_cb_holder) {
+            m_cb_holder.reset(new CallbacksHolder(trampoline, deleter));
         }
-        return *m_callbacks.get();
+        m_cb_holder->add(event, cb);
     }
 
     void call(const std::string& event) {
-        if (!m_callbacks)
+        if (!m_cb_holder)
             return;
-        auto itr = m_callbacks->find(event);
-        if (itr != m_callbacks->end()) {
-            (*m_cb_trampoline)(itr->second, this);
-        }
+        m_cb_holder->call(this, event);
     }
 
     void markChangedLocked(const std::string& key);
@@ -83,10 +123,7 @@ class WidgetState {
     bool remarkAllChanges();
 
     rbjson::Object m_data;
-    const cb_trampoline_t m_cb_trampoline;
-    std::unique_ptr<std::map<std::string, void*>> m_callbacks;
-
-    mutable std::mutex m_mutex;
+    std::unique_ptr<CallbacksHolder> m_cb_holder;
 
     const uint16_t m_uuid;
 
diff --git a/test-inis/esp32-idf3-arduino.ini b/test-inis/esp32-idf3-arduino.ini
index 479d4e3b..2f69d687 100644
--- a/test-inis/esp32-idf3-arduino.ini
+++ b/test-inis/esp32-idf3-arduino.ini
@@ -23,4 +23,4 @@ build_flags =
     -fmax-errors=5
     -DLX16A_ARDUINO=1
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32-idf4-arduino.ini b/test-inis/esp32-idf4-arduino.ini
index b0f6ab92..90bc55e5 100644
--- a/test-inis/esp32-idf4-arduino.ini
+++ b/test-inis/esp32-idf4-arduino.ini
@@ -23,4 +23,4 @@ build_flags =
     -fmax-errors=5
     -DLX16A_ARDUINO=1
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32-idf5-idf.ini b/test-inis/esp32-idf5-idf.ini
index d6712a08..128547c2 100644
--- a/test-inis/esp32-idf5-idf.ini
+++ b/test-inis/esp32-idf5-idf.ini
@@ -22,4 +22,4 @@ build_flags =
     -std=gnu++14
     -fmax-errors=5
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32c3-idf4-arduino.ini b/test-inis/esp32c3-idf4-arduino.ini
index 30b34a34..d5e5c3f1 100644
--- a/test-inis/esp32c3-idf4-arduino.ini
+++ b/test-inis/esp32c3-idf4-arduino.ini
@@ -23,4 +23,4 @@ build_flags =
     -fmax-errors=5
     -DLX16A_ARDUINO=1
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32c3-idf5-idf.ini b/test-inis/esp32c3-idf5-idf.ini
index f6abeeae..1dfb01c4 100644
--- a/test-inis/esp32c3-idf5-idf.ini
+++ b/test-inis/esp32c3-idf5-idf.ini
@@ -22,4 +22,4 @@ build_flags =
     -std=gnu++14
     -fmax-errors=5
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32s3-idf4-arduino.ini b/test-inis/esp32s3-idf4-arduino.ini
index 0466ae8f..d84e17c2 100644
--- a/test-inis/esp32s3-idf4-arduino.ini
+++ b/test-inis/esp32s3-idf4-arduino.ini
@@ -23,4 +23,4 @@ build_flags =
     -fmax-errors=5
     -DLX16A_ARDUINO=1
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip
diff --git a/test-inis/esp32s3-idf5-idf.ini b/test-inis/esp32s3-idf5-idf.ini
index d7df2a56..be4a40eb 100644
--- a/test-inis/esp32s3-idf5-idf.ini
+++ b/test-inis/esp32s3-idf5-idf.ini
@@ -22,4 +22,4 @@ build_flags =
     -std=gnu++14
     -fmax-errors=5
 
-lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v12.0.0.zip
+lib_deps = https://github.com/RoboticsBrno/RB3201-RBProtocol-library/archive/refs/tags/v13.0.0.zip