Fixed positioning of gizmos' imgui dialogs

src/slic3r/GUI/3DBed.hpp

@@ -86,8 +86,6 @@ private:
     mutable GLTexture m_texture;
     // temporary texture shown until the main texture has still no levels compressed
     mutable GLTexture m_temp_texture;
-    // used to trigger 3D scene update once all compressed textures have been sent to GPU
-    mutable bool m_requires_canvas_update;
     mutable Shader m_shader;
     mutable unsigned int m_vbo_id;
     mutable GLBed m_model;