refactor canvas modes

src/node_button.h

@@ -5,12 +5,14 @@
 
 class NodeButton : public Node
 {
+    bool m_active = false;
 public:
     NodeBorder* m_border;
     NodeText* m_text;
     glm::vec4 color_normal{ .1, .1, .1, 1 };
     glm::vec4 color_hover{ .2, .2, .2, 1 };
     glm::vec4 color_down{ .3, .3, .3, 1 };
+    glm::vec4 color_active{ 1, 0, 0, 1 };
     std::function<void(Node* target)> on_click;
     virtual Node* clone_instantiate() const override;
     virtual void clone_children(Node* dest) const override;
@@ -19,6 +21,7 @@ public:
     virtual void create() override;
     virtual void loaded() override;
     virtual void parse_attributes(kAttribute ka, const tinyxml2::XMLAttribute* attr) override;
+    void set_active(bool active);
     void set_color(const glm::vec4& c);
     virtual kEventResult handle_event(Event* e) override;
 };