When performing an overlay or intersect I would like to know if there is a way to ignore selection when intersection or overlay is less than a certain percentage of area or less than a certain number of crossing map units of the perimeter of a polygon.
The "Select Within" plugin will allow you to do mostly within selections.
So you can supply a % number. So you can select all of the features from a layer that are at least 50% within the selecting layer.
So you could run that, and create a selection, then run the overlay or intersection using only the selected features.