This plugin is intended as a workaround for a bug in pstoedit. Pstodeit generates polygons instead of polygon holes. This plugin creates a polystitch action that can fix up that case. The polystitch action shall be ran while the crosshair is over the inner polygon of two overlapping polygons. The action takes the inner polygon and converts it into a hole within the outer polygon then removes the inner polygon.
The plugin assumes that there are only two polygons under the crosshair and the inner polygon is fully within the outer polygon.
The thindraw or wireframe view mode may be of help in searching such overlapping polygons.