FIX: STUDIO-632

cut gizmo: the grabber does not move to original position when press reset button

Change-Id: Ia4e47b9470e66348dea53947c8dc3e4b6bb255e8
(cherry picked from commit 7b783492af5d502a6b93df7d0c8360673f00edff)

src/slic3r/GUI/Gizmos/GLGizmoAdvancedCut.cpp

@@ -154,6 +154,7 @@ void GLGizmoAdvancedCut::reset_cut_plane()
     m_cut_plane_points[3] = { min_x, max_y, 0 };
     m_movement = 0.0;
     m_height = box.size()[2] / 2.0;
+    m_buffered_height     = m_height;
     m_height_delta = 0;
     m_rotation.setZero();
     //m_current_base_rotation.setZero();