This time the screen image is not a repeating gradient, but a pattern fill.
Working with inkscape it turned out that the use process is rather different than the mentioned points. The basic of the problem is the resulting image traced can end up 100k+ nodes, likely having a performance issue. Then, it means it's easier just to generate a raster copy and trace it outside.
My workflow is the following: import a photograph into the template file in inkscape,
create a raster copy (Alt+B). It results in a raster image generated in the svg template's folder.
Then, uploading that raster image to potrace at openclipart.org.
collection of screen template files
wavy screen template
sayagata screen template
wave-dot screen template
diagonal screen template
cross screen template