issue about igure (irregular width of a box around a map using "Painters" renderer)

Folks

I have an issue when I plot a figure. The box around the map appears to be irregular (for example, south of Pacific in the attached figure). I tried to set the width of the box to a specific value using 'linewidth' option in m_grid but it doesn't solve the issue. I tried also to add a box using m_plot, but it doesn't solve this issue. When I use OpenGL renderer,matlab crashes before plotting the figures. The figure is produced with Painters renderer. "Z-buffer" does not work on my machine (ubuntu 16.04 on a Dell Precision 7520). The issue is also seen on the graphic window of matlab before the saving under jpeg.

Any help is welcome

Vincent Moron