TGraph: inconsistency between actual plot and legend

Hi all!
I’ve come with this little example for a situation I’m dealing with

void leg(){
   Double_t x[100], y[100];
   Int_t n = 20;
   for (Int_t i=0; i < n; i++) y[i] = - (x[i] = i);
   TCanvas *c1 = new TCanvas("c1","",200,10,700,500);
   gr = new TGraph(n,x,y);

What I get is attached. The problem I see with that outcome is that the legend doesn’t honor what’s shown in the actual plot: in the plot only the marker is used, whereas in the legend all the Fill/Line/Marker attributes are used.
I’d like to have only the marker in the legend, with no line or fill atributes (if the fill attributes are set to hollow, a bounding box with fill color is shown nevertheless).
Am I doing something wrong, or have misunderstood something? A workaround may be to set the fill and line color according to the canvas’ fill color.
Thanks a lot for your help.

This is how BuildLegend is work, See:

BuilLegend is a shortcut to make quickly a Legend from all the objects in the Pad. All the attributes are taken into account.
In a simple case like yours I do not think BuilLegend is the best way to go. I guess building the legend yourself is not more complicate.

Thanks a lot for your help, and for the reference. Cheers.