grImport2 can import complex SVG

R cannot replicate complex SVG

gridSVG can generate complex SVG

this means that we can import complex SVG with grImport2
and output it with  gridSVG

an example of complex SVG is a mask.
This is complex both because it is a mask and because the 
definition of a mask is context-sensitive (to the current grid viewport).
Show example

when we import from SVG and export to SVG we have to be careful
when we create the SVG definitions to export.
By default, this happens when we create a pictureGrob.
If we are exporting SVG that contains a mask, we need to create
the pictureGrob within the right viewport or it will not be right.