When sketching, it may happen to have overlapping lines, and they are messy because is difficult to realize that some parts of the drawings are multiple or stacked. It would be a nice feature that when there are more than one line/curve that overlaps, the overlapping part is in a different colour.
This would immediately highlight what is wrong on a sketch.
In the mockup example below, the yellow lines are residual lines of the sketch evolution that after several draw and cut, survived hidden, because they are exactly below or up the final lines. When they are blue they are almost impossible to find.
With this new feature they would be immediately visible and they could be checked and deleted, and it would avoid problems in further design steps.
