GLCanvas3D -> added support for cursor change and change cursor when using SLA support gizmo rectangle selection

src/slic3r/GUI/GLCanvas3D.hpp

@@ -392,6 +392,14 @@ private:
         void render(const GLCanvas3D& canvas) const;
     };
 
+public:
+    enum ECursorType : unsigned char
+    {
+        Standard,
+        Cross
+    };
+
+private:
     wxGLCanvas* m_canvas;
     wxGLContext* m_context;
 #if ENABLE_RETINA_GL
@@ -436,6 +444,7 @@ private:
     bool m_regenerate_volumes;
     bool m_moving;
     bool m_tab_down;
+    ECursorType m_cursor_type;
 
     // Following variable is obsolete and it should be safe to remove it.
     // I just don't want to do it now before a release (Lukas Matena 24.3.2019)
@@ -587,6 +596,8 @@ public:
 
     double get_size_proportional_to_max_bed_size(double factor) const;
 
+    void set_cursor(ECursorType type);
+
 private:
     bool _is_shown_on_screen() const;