Ok, first and foremost thanks again for replying to my question in such a detailed way, you Sir are a gentleman and a scholar! :)
I believe I've got a problem though.
When I open your files with Inkscape I either see a blank document (air_litho) or this (air_litho2):

Am I supposed to see anything else? I'm currently using the version 0.46, could it be a compatibility issue?
Assuming it's actually a compatibility issue, how do you update to a more recent version (I know you can have 2 versions of Inkscape on the same PC at the same time if at least one of them is "portable" and not installed but that's not my aim)?
Would uninstalling the 0.46 version and installing ex-novo the 0.48 one bring forth compatibility issues with the files that were created on the older version or is it a safe process that doesn't harm the files in any way, shape or form?
ivan louette wrote:
Bonus : I added a second filter where you can change the two colors and make them progressively transparent. Only work with the same effects as over + the two Flood effects for color and Color opacity.
Here are the commands (when you find the same effect several times I give them a number to simplify their localization in the tree) :
hmm, where exactly am I supposed to find this "tree" and these filters though (under "filters" I got only a few of the ones that were mentioned in your walkthrough).
Perhaps this stuff isn't accessible in the 0.46 version or is it just me being a total noob?
Thanks again for your patience.