diff --git a/include/application.h b/include/application.h
index 1702e7a..4c1e030 100644
--- a/include/application.h
+++ b/include/application.h
@@ -18,7 +18,7 @@ public:
     Application();
     void run();
     void input();
-    void update();
+    void update(const sf::Time& dt);
     void draw();
 
 private:
diff --git a/include/gui/state.h b/include/gui/state.h
index 6652ab8..f07b017 100644
--- a/include/gui/state.h
+++ b/include/gui/state.h
@@ -24,7 +24,7 @@ public:
     virtual ~GUIState() = default;
 
     virtual void input(const sf::Event& event) = 0;
-    virtual void update() = 0;
+    virtual void update(const sf::Time& dt) = 0;
     virtual void draw() const = 0;
 
     virtual void enter() = 0;
diff --git a/include/tools/bpmcalculator.h b/include/tools/bpmcalculator.h
index 04ae469..72f5ba1 100644
--- a/include/tools/bpmcalculator.h
+++ b/include/tools/bpmcalculator.h
@@ -10,8 +10,7 @@ public:
     explicit BPMCalculator(const std::shared_ptr<Music>& music);
     void setMusic(const std::shared_ptr<Music>& music);
 
-    void startListening(const microsec& offset);
-    void stopListening();
+    void start();
 
     void click();
     int getCurrentApproximation() const;
diff --git a/src/application.cpp b/src/application.cpp
index 0c1a1df..1dc4fd8 100644
--- a/src/application.cpp
+++ b/src/application.cpp
@@ -60,7 +60,7 @@ void Application::exec()
         if (isOneFramePassed)
         {
             time_since_last_update -= TIME_PER_FRAME;
-            update();
+            update(time_since_last_update);
             draw();
         }
     }
@@ -84,9 +84,9 @@ void Application::input()
     }
 }
 
-void Application::update()
+void Application::update(const sf::Time& dt)
 {
-    _state_stack.back()->update();
+    _state_stack.back()->update(dt);
 }
 
 void Application::draw()
diff --git a/src/gui/editor.cpp b/src/gui/editor.cpp
index 1f33bcd..a9faad3 100644
--- a/src/gui/editor.cpp
+++ b/src/gui/editor.cpp
@@ -2,6 +2,7 @@
 #include "widgets/button.h"
 #include "widgets/group.h"
 #include "widgets/menubar.h"
+#include "widgets/bpmcalculatorwidget.h"
 #include "tools/bpmcalculator.h"
 
 #include <iostream>
@@ -9,7 +10,8 @@
 Editor::Editor(sf::RenderWindow& game_window, Callbacks&& callbacks, std::unique_ptr<Music>&& music, const FontHolder& font_holder) :
     _game_window(game_window),
     _music(std::move(music)),
-    _bpm_calculator(std::make_unique<BPMCalculator>(_music))
+    _bpm_calculator(std::make_shared<BPMCalculator>(_music)),
+    _bpm_widget(std::make_shared<BPMCalculatorWidget>(_bpm_calculator, font_holder.get(Fonts::Id::GUI)))
 {
     (void)callbacks;
     const float window_width = game_window.getSize().x;
@@ -20,14 +22,22 @@ Editor::Editor(sf::RenderWindow& game_window, Callbacks&& callbacks, std::unique
     auto bpm_button = std::make_shared<PushButton>("Play song :)", font_holder.get(Fonts::Id::GUI));
     bpm_button->setCallback([&]()
                             {
-                                _bpm_calculator->startListening(0);
+                                _bpm_widget->setVisibility(true);
                             });
 
+    _bpm_widget->setRect(sf::FloatRect(_game_window.getSize().x / 3, _game_window.getSize().y / 3, _game_window.getSize().x / 3, _game_window.getSize().y / 3));
+    _bpm_widget->setVisibility(false);
+
     auto test_menu_2 = std::make_shared<MenuDrop>();
     test_menu_2->setRect(sf::FloatRect{0, 0, 200, 27 * 5});
 
+    auto test_menu_3 = std::make_shared<MenuDrop>();
+    test_menu_3->setRect(sf::FloatRect{0, 0, 200, 27 * 5});
+
     auto test_cascade_button = std::make_shared<CascadeMenuButton>("Show submenu", font_holder.get(Fonts::Id::GUI));
 
+    auto test_cascade_button_2 = std::make_shared<CascadeMenuButton>("Show submenu 2", font_holder.get(Fonts::Id::GUI));
+
     auto quit_button = std::make_shared<PushButton>("Quit", font_holder.get(Fonts::Id::GUI));
     quit_button->setCallback(callbacks.onLeaveEditorState);
 
@@ -45,6 +55,10 @@ Editor::Editor(sf::RenderWindow& game_window, Callbacks&& callbacks, std::unique
 
     test_cascade_button->resetRect();
 
+    test_cascade_button_2->setSubmenu(test_menu_3);
+    test_menu_2->addCascadeButton(test_cascade_button_2);
+    test_cascade_button_2->resetRect();
+
     _music->openFromFile("Uta-test.flac");
     _music->setVolume(5);
 }
@@ -52,22 +66,18 @@ Editor::Editor(sf::RenderWindow& game_window, Callbacks&& callbacks, std::unique
 void Editor::input(const sf::Event& event)
 {
     _menu_bar->input(event);
-
-    if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Space)
-    {
-        _bpm_calculator->click();
-        std::cout << _bpm_calculator->getCurrentApproximation() << '\n';
-    }
 }
 
-void Editor::update()
+void Editor::update(const sf::Time& dt)
 {
-    _menu_bar->update();
+    _menu_bar->update(dt);
+    _bpm_widget->update(dt);
 }
 
 void Editor::draw() const
 {
     _game_window.draw(*_menu_bar);
+    _game_window.draw(*_bpm_widget);
 }
 
 void Editor::enter()
diff --git a/src/gui/editor.h b/src/gui/editor.h
index faa36d0..60d4e9a 100644
--- a/src/gui/editor.h
+++ b/src/gui/editor.h
@@ -6,6 +6,7 @@
 #include <SFML/Graphics/RenderWindow.hpp>
 
 class MenuBar;
+class BPMCalculatorWidget;
 class BPMCalculator;
 
 class Editor : public GUIState
@@ -19,7 +20,7 @@ public:
 
     explicit Editor(sf::RenderWindow& game_window, Callbacks&& callbacks, std::unique_ptr<Music>&& music, const FontHolder& font_holder);
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw() const override;
 
     virtual void enter() override;
@@ -31,5 +32,6 @@ private:
 
     std::shared_ptr<Music> _music;
     std::shared_ptr<BPMCalculator> _bpm_calculator;
+    std::shared_ptr<BPMCalculatorWidget> _bpm_widget;
 };
 
diff --git a/src/gui/gamestate.cpp b/src/gui/gamestate.cpp
index a5af5b2..d7fb41b 100644
--- a/src/gui/gamestate.cpp
+++ b/src/gui/gamestate.cpp
@@ -16,8 +16,13 @@ void GameState::input(const sf::Event& event)
     _game->input({0, event});
 }
 
-void GameState::update()
+void GameState::update(const sf::Time& dt)
 {
+    (void)dt;
+    // !!!!!!!!!!!!!!!!!!!!!!
+    // TODO.
+    //
+    // Oh dude... hang in there
     _game->update();
 }
 
diff --git a/src/gui/gamestate.h b/src/gui/gamestate.h
index 68be7d0..d4482d2 100644
--- a/src/gui/gamestate.h
+++ b/src/gui/gamestate.h
@@ -21,7 +21,7 @@ public:
                        Callbacks&& callbacks);
 
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw() const override;
 
     virtual void enter() override;
diff --git a/src/gui/mainmenu.cpp b/src/gui/mainmenu.cpp
index ec6e43e..e393740 100644
--- a/src/gui/mainmenu.cpp
+++ b/src/gui/mainmenu.cpp
@@ -29,9 +29,9 @@ void MainMenu::input(const sf::Event& event)
     _buttons->input(event);
 }
 
-void MainMenu::update()
+void MainMenu::update(const sf::Time& dt)
 {
-    _buttons->update();
+    _buttons->update(dt);
 }
 
 void MainMenu::draw() const
diff --git a/src/gui/mainmenu.h b/src/gui/mainmenu.h
index c79e37d..a2d4c78 100644
--- a/src/gui/mainmenu.h
+++ b/src/gui/mainmenu.h
@@ -17,7 +17,7 @@ public:
 
     explicit MainMenu(sf::RenderWindow& game_window, Callbacks&& callbacks, const FontHolder &font_holder);
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw() const override;
 
     virtual void enter() override;
diff --git a/src/gui/widgets/bpmcalculatorwidget.cpp b/src/gui/widgets/bpmcalculatorwidget.cpp
index a37c444..f022bd9 100644
--- a/src/gui/widgets/bpmcalculatorwidget.cpp
+++ b/src/gui/widgets/bpmcalculatorwidget.cpp
@@ -1,10 +1,12 @@
 #include "bpmcalculatorwidget.h"
+#include "tools/bpmcalculator.h"
 
-BPMCalculatorWidget::BPMCalculatorWidget() :
-    _pressed(false)
+BPMCalculatorWidget::BPMCalculatorWidget(const std::shared_ptr<BPMCalculator>& bpm_calculator, const std::shared_ptr<sf::Font>& font) :
+    _bpm_calculator(bpm_calculator),
+    _slider(std::make_shared<BPMSlider>(font))
 {
-    _button_text.setFillColor(sf::Color::Black);
-    _button_content.setFillColor(sf::Color::White);
+    _widget_window.setFillColor(sf::Color(88, 57, 107));
+    //addChild(_slider);
 }
 
 void BPMCalculatorWidget::input(const sf::Event& event)
@@ -14,21 +16,10 @@ void BPMCalculatorWidget::input(const sf::Event& event)
     default:
         break;
 
-    case sf::Event::MouseButtonPressed:
-        if (isUnderMouse(event.mouseButton.x, event.mouseButton.y))
+    case sf::Event::KeyPressed:
+        if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Space)
         {
-            _pressed = true;
-            _button_content.setFillColor(sf::Color(155, 155, 155));
-        }
-        break;
-
-    case sf::Event::MouseButtonReleased:
-        if (_pressed)
-        {
-            _button_content.setFillColor(sf::Color::White);
-            _pressed = false;
-            if (isUnderMouse(event.mouseButton.x, event.mouseButton.y))
-                _on_click_callback();
+            _bpm_calculator->click();
         }
         break;
     }
@@ -36,31 +27,36 @@ void BPMCalculatorWidget::input(const sf::Event& event)
     Widget::input(event);
 }
 
-void BPMCalculatorWidget::update()
+void BPMCalculatorWidget::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void BPMCalculatorWidget::draw(sf::RenderTarget& target, sf::RenderStates states) const
 {
-    target.draw(_button_content, states);
-    target.draw(_button_text, states);
-
-    Widget::draw(target, states);
+    if (_is_visible)
+    {
+        target.draw(_widget_window, states);
+        Widget::draw(target, states);
+    }
 }
 
 void BPMCalculatorWidget::setRect(const sf::FloatRect& rect)
 {
-    _button_content.setPosition(rect.left, rect.top);
-    _button_content.setSize({rect.width, rect.height});
+    _widget_window.setPosition(rect.left, rect.top);
+    _widget_window.setSize({rect.width, rect.height});
+    _slider->setRect(sf::FloatRect{rect.width / 3, rect.height / 2 - 50, rect.width / 3, 100});
 }
 
 void BPMCalculatorWidget::setPosition(const sf::Vector2f &position)
 {
-    _button_content.setPosition(position);
+    _widget_window.setPosition(position);
+    _slider->setRect(sf::FloatRect{_widget_window.getSize().x / 3,
+                                   _widget_window.getSize().y / 2 - 50,
+                                   _widget_window.getSize().x / 3, 100});
 }
 
 bool BPMCalculatorWidget::isUnderMouse(int mouse_x, int mouse_y) const
 {
-    return _button_content.getGlobalBounds().contains(mouse_x, mouse_y);
+    return _is_visible && _widget_window.getGlobalBounds().contains(mouse_x, mouse_y);
 }
diff --git a/src/gui/widgets/bpmcalculatorwidget.h b/src/gui/widgets/bpmcalculatorwidget.h
index b5b4aae..943dc57 100644
--- a/src/gui/widgets/bpmcalculatorwidget.h
+++ b/src/gui/widgets/bpmcalculatorwidget.h
@@ -1,26 +1,30 @@
 #pragma once
 
 #include "widget.h"
+#include "bpmslider.h"
 #include <functional>
 #include <SFML/Graphics/RectangleShape.hpp>
 #include <SFML/Graphics/Text.hpp>
 
+class BPMCalculator;
+
 class BPMCalculatorWidget : public Widget
 {
 public:
-    BPMCalculatorWidget();
+    explicit BPMCalculatorWidget(const std::shared_ptr<BPMCalculator>& bpm_calculator, const std::shared_ptr<sf::Font> &font);
 
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
     virtual void setRect(const sf::FloatRect& rect) override;
     virtual void setPosition(const sf::Vector2f& position) override;
     virtual bool isUnderMouse(int mouse_x, int mouse_y) const override;
 
 private:
-    sf::RectangleShape _button_content;
-    sf::Text _button_text;
-    bool _pressed;
+    std::shared_ptr<BPMCalculator> _bpm_calculator;
+    std::shared_ptr<BPMSlider> _slider;
+
+    sf::RectangleShape _widget_window;
 
     std::function<void(void)> _on_click_callback;
 };
diff --git a/src/gui/widgets/bpmslider.cpp b/src/gui/widgets/bpmslider.cpp
new file mode 100644
index 0000000..349bf27
--- /dev/null
+++ b/src/gui/widgets/bpmslider.cpp
@@ -0,0 +1,38 @@
+#include "bpmslider.h"
+
+BPMSlider::BPMSlider(const std::shared_ptr<sf::Font> &font)
+{
+    _bpm_value.setFont(*font);
+}
+
+void BPMSlider::input(const sf::Event& event)
+{
+    Widget::input(event);
+}
+
+void BPMSlider::update(const sf::Time& dt)
+{
+    Widget::update(dt);
+}
+
+void BPMSlider::draw(sf::RenderTarget& target, sf::RenderStates states) const
+{
+    Widget::draw(target, states);
+}
+
+void BPMSlider::setRect(const sf::FloatRect& rect)
+{
+    _slider_background.setPosition(rect.left, rect.top);
+    _slider_background.setSize({rect.width, rect.height});
+}
+
+void BPMSlider::setPosition(const sf::Vector2f& position)
+{
+    _slider_background.setPosition(position);
+}
+
+bool BPMSlider::isUnderMouse(int mouse_x, int mouse_y) const
+{
+    return mouse_x == mouse_y; // just to compile
+}
+
diff --git a/src/gui/widgets/bpmslider.h b/src/gui/widgets/bpmslider.h
new file mode 100644
index 0000000..81a1641
--- /dev/null
+++ b/src/gui/widgets/bpmslider.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "widget.h"
+
+#include <SFML/Graphics/RectangleShape.hpp>
+#include <SFML/Graphics/Text.hpp>
+
+class BPMSlider : public Widget
+{
+public:
+    explicit BPMSlider(const std::shared_ptr<sf::Font> &font);
+
+    virtual void input(const sf::Event& event) override;
+    virtual void update(const sf::Time& dt) override;
+    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
+    virtual void setRect(const sf::FloatRect& rect) override;
+    virtual void setPosition(const sf::Vector2f& position) override;
+    virtual bool isUnderMouse(int mouse_x, int mouse_y) const override;
+
+private:
+    sf::RectangleShape _slider_background;
+    sf::RectangleShape _slider_tick;
+    sf::Text _bpm_value;
+};
+
+
diff --git a/src/gui/widgets/button.cpp b/src/gui/widgets/button.cpp
index df41122..f6705df 100644
--- a/src/gui/widgets/button.cpp
+++ b/src/gui/widgets/button.cpp
@@ -9,9 +9,9 @@ Button::Button(const std::string &text, const std::shared_ptr<sf::Font>& font, u
     _button_text.setFont(*_font);
 }
 
-void Button::update()
+void Button::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void Button::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/button.h b/src/gui/widgets/button.h
index 0209916..343745e 100644
--- a/src/gui/widgets/button.h
+++ b/src/gui/widgets/button.h
@@ -11,7 +11,7 @@ public:
     explicit Button(const std::string& text, const std::shared_ptr<sf::Font>& font, unsigned int font_size);
 
     virtual void input(const sf::Event& event) override = 0;
-    virtual void update() override final;
+    virtual void update(const sf::Time& dt) override final;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override final;
     virtual void setPosition(const sf::Vector2f& position) override final;
     virtual bool isUnderMouse(int mouse_x, int mouse_y) const override final;
diff --git a/src/gui/widgets/group.cpp b/src/gui/widgets/group.cpp
index 645a2e8..6587f24 100644
--- a/src/gui/widgets/group.cpp
+++ b/src/gui/widgets/group.cpp
@@ -5,9 +5,9 @@ void Group::input(const sf::Event& event)
     Widget::input(event);
 }
 
-void Group::update()
+void Group::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void Group::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/group.h b/src/gui/widgets/group.h
index 8ebe145..7e71334 100644
--- a/src/gui/widgets/group.h
+++ b/src/gui/widgets/group.h
@@ -6,7 +6,7 @@ class Group : public Widget
 {
 public:
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
     virtual void setRect(const sf::FloatRect& rect) override;
     virtual void setPosition(const sf::Vector2f& position) override;
diff --git a/src/gui/widgets/menubar.cpp b/src/gui/widgets/menubar.cpp
index d9f65c3..2378959 100644
--- a/src/gui/widgets/menubar.cpp
+++ b/src/gui/widgets/menubar.cpp
@@ -27,9 +27,9 @@ void MenuBar::input(const sf::Event &event)
     Widget::input(event);
 }
 
-void MenuBar::update()
+void MenuBar::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void MenuBar::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/menubar.h b/src/gui/widgets/menubar.h
index 60151ab..a3e6ad5 100644
--- a/src/gui/widgets/menubar.h
+++ b/src/gui/widgets/menubar.h
@@ -12,7 +12,7 @@ public:
     explicit MenuBar(const std::shared_ptr<sf::Font>& font);
 
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
     virtual void setRect(const sf::FloatRect& rect) override;
     virtual void setPosition(const sf::Vector2f& position) override;
diff --git a/src/gui/widgets/menudrop.cpp b/src/gui/widgets/menudrop.cpp
index 3040afb..0851299 100644
--- a/src/gui/widgets/menudrop.cpp
+++ b/src/gui/widgets/menudrop.cpp
@@ -42,9 +42,9 @@ bool MenuDrop::hasActiveSubmenus() const
                        });
 }
 
-void MenuDrop::update()
+void MenuDrop::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void MenuDrop::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/menudrop.h b/src/gui/widgets/menudrop.h
index 579ba3c..1046bff 100644
--- a/src/gui/widgets/menudrop.h
+++ b/src/gui/widgets/menudrop.h
@@ -11,7 +11,7 @@ public:
     explicit MenuDrop();
 
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
     virtual void setRect(const sf::FloatRect& rect) override;
     virtual void setPosition(const sf::Vector2f& position) override;
diff --git a/src/gui/widgets/menuseparator.cpp b/src/gui/widgets/menuseparator.cpp
index 3d044fa..44e2ad5 100644
--- a/src/gui/widgets/menuseparator.cpp
+++ b/src/gui/widgets/menuseparator.cpp
@@ -5,9 +5,9 @@ void MenuSeparator::input(const sf::Event& event)
     Widget::input(event);
 }
 
-void MenuSeparator::update()
+void MenuSeparator::update(const sf::Time& dt)
 {
-    Widget::update();
+    Widget::update(dt);
 }
 
 void MenuSeparator::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/menuseparator.h b/src/gui/widgets/menuseparator.h
index e928345..fe3c522 100644
--- a/src/gui/widgets/menuseparator.h
+++ b/src/gui/widgets/menuseparator.h
@@ -8,7 +8,7 @@ class MenuSeparator : public Widget
 {
 public:
     virtual void input(const sf::Event& event) override;
-    virtual void update() override;
+    virtual void update(const sf::Time& dt) override;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
     virtual void setRect(const sf::FloatRect& rect) override;
     virtual void setPosition(const sf::Vector2f& position) override;
diff --git a/src/gui/widgets/widget.cpp b/src/gui/widgets/widget.cpp
index 96dbb22..75a2f9d 100644
--- a/src/gui/widgets/widget.cpp
+++ b/src/gui/widgets/widget.cpp
@@ -11,10 +11,10 @@ void Widget::input(const sf::Event &event)
     }
 }
 
-void Widget::update()
+void Widget::update(const sf::Time& dt)
 {
     for (auto& child : _children)
-        child->update();
+        child->update(dt);
 }
 
 void Widget::draw(sf::RenderTarget& target, sf::RenderStates states) const
diff --git a/src/gui/widgets/widget.h b/src/gui/widgets/widget.h
index 593ac9f..0d81d44 100644
--- a/src/gui/widgets/widget.h
+++ b/src/gui/widgets/widget.h
@@ -12,7 +12,7 @@ public:
     virtual ~Widget() = default;
 
     virtual void input(const sf::Event& event) = 0;
-    virtual void update() = 0;
+    virtual void update(const sf::Time& dt) = 0;
     virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const = 0;
     virtual void setRect(const sf::FloatRect& rect) = 0;
     virtual void setPosition(const sf::Vector2f& position) = 0;
diff --git a/src/tools/bpmcalculator.cpp b/src/tools/bpmcalculator.cpp
index 30d9e02..a1ce4ac 100644
--- a/src/tools/bpmcalculator.cpp
+++ b/src/tools/bpmcalculator.cpp
@@ -17,17 +17,10 @@ void BPMCalculator::setMusic(const std::shared_ptr<Music>& music)
     _music = music;
 }
 
-void BPMCalculator::startListening(const microsec &offset)
+void BPMCalculator::start()
 {
     _deltas.clear();
-    _previous_click_offset = 0;
-    _music->setOffset(offset);
-    _music->play();
-}
-
-void BPMCalculator::stopListening()
-{
-    _music->stop();
+    _previous_click_offset = _music->fetchOffset();
 }
 
 void BPMCalculator::click()
@@ -36,7 +29,7 @@ void BPMCalculator::click()
 
     std::cout << click_offset << "\n\n\n\n";
 
-    if (_previous_click_offset == 0)
+    if (_deltas.empty())
     {
         _previous_click_offset = click_offset;
         return;