add free and poly selection mask tools, fix some threading gl problems

engine/canvas_modes.h

@@ -92,6 +92,19 @@ public:
 };
 
 class CanvasModeFill : public CanvasMode
+{
+    ui::DynamicShape m_shape;
+    bool m_dragging = false;
+    std::vector<ui::Shape::vertex_t> m_points;
+    std::map<int, int> m_dirty_planes;
+public:
+    virtual void on_Draw(const glm::mat4& ortho, const glm::mat4& proj, const glm::mat4& camera) override;
+    virtual void on_MouseEvent(MouseEvent* me, glm::vec2& loc) override;
+    virtual void init() override;
+    virtual void leave() override;
+};
+
+class CanvasModeMaskFree : public CanvasMode
 {
     ui::DynamicShape m_shape;
     bool m_dragging = false;