LibGUI: Add Button double-click callback

Userland/Libraries/LibGUI/AbstractButton.cpp

@@ -160,6 +160,12 @@ void AbstractButton::mouseup_event(MouseEvent& event)
     Widget::mouseup_event(event);
 }
 
+void AbstractButton::doubleclick_event(GUI::MouseEvent& event)
+{
+    double_click(event.modifiers());
+    Widget::doubleclick_event(event);
+}
+
 void AbstractButton::enter_event(Core::Event&)
 {
     m_hovered = true;

Userland/Libraries/LibGUI/AbstractButton.h

@@ -41,7 +41,8 @@ public:
     void set_allowed_mouse_buttons_for_pressing(unsigned allowed_buttons) { m_allowed_mouse_buttons_for_pressing = allowed_buttons; }
 
     virtual void click(unsigned modifiers = 0) = 0;
-    virtual void middle_mouse_click(unsigned) {};
+    virtual void double_click(unsigned) { }
+    virtual void middle_mouse_click(unsigned) { }
     virtual bool is_uncheckable() const { return true; }
 
     int auto_repeat_interval() const { return m_auto_repeat_interval; }
@@ -53,6 +54,7 @@ protected:
     virtual void mousedown_event(MouseEvent&) override;
     virtual void mousemove_event(MouseEvent&) override;
     virtual void mouseup_event(MouseEvent&) override;
+    virtual void doubleclick_event(GUI::MouseEvent&) override;
     virtual void keydown_event(KeyEvent&) override;
     virtual void keyup_event(KeyEvent&) override;
     virtual void enter_event(Core::Event&) override;

Userland/Libraries/LibGUI/Button.cpp

@@ -145,6 +145,12 @@ void Button::click(unsigned modifiers)
         m_action->activate(this);
 }
 
+void Button::double_click(unsigned int modifiers)
+{
+    if (on_double_click)
+        on_double_click(modifiers);
+}
+
 void Button::middle_mouse_click(unsigned int modifiers)
 {
     if (!is_enabled())

Userland/Libraries/LibGUI/Button.h

@@ -37,6 +37,7 @@ public:
     Gfx::TextAlignment text_alignment() const { return m_text_alignment; }
 
     Function<void(unsigned modifiers)> on_click;
+    Function<void(unsigned modifiers)> on_double_click;
     Function<void(unsigned modifiers)> on_middle_mouse_click;
     Function<void(ContextMenuEvent&)> on_context_menu_request;
 
@@ -44,6 +45,7 @@ public:
     Gfx::ButtonStyle button_style() const { return m_button_style; }
 
     virtual void click(unsigned modifiers = 0) override;
+    virtual void double_click(unsigned modifiers = 0) override;
     virtual void middle_mouse_click(unsigned modifiers = 0) override;
     virtual void context_menu_event(ContextMenuEvent&) override;