I recently came across Using boundaries of city to cover world outside of it in solid color? on GIS SE. Let me preface this by saying I have particular interest in helping out new SE and/or GIS users. I'm not totally sure where the asker's experience level is with QGIS but I'm guessing it's a relatively new field for him. To me, it seems pretty inhospitable to shove this guys question aside and direct him to a confusing pyQGIS answer that likely wont meet his needs as a new GIS user.
Inverting Polygons using QGIS? is a more similar question that I would accept as being a duplicate to the first linked post. It was also marked as a duplicate to the pyQGIS question. (But in my opinion they are completely different q&a's because the accepted answers are very distinct approaches).
Basically I think the two posts I've linked to should be duplicates of each other but should not be duplicates of the coding post.
Is it fair to keep GUI questions/solutions separate from coding ones? I feel they both have distinct value in this community.