Transparent style to fill histogram

Hi, I want use for an histogram a transparent color to fill the area. Reading the user manual seems that setting the fill style in the range 4000-4100 I will obtain this result but i obtain only a fully transparent fill style, why?

this is the code for the example:

   TH1F *histo = new TH1F("histo","Histo",50,-4,4);


   TCanvas *c1 = new TCanvas("c1","Canvas",1);



   histo->Draw("e bar");

I need to compile ROOT with a particular version of some graphich library?

The TAttFill help says:

4000 :the window is transparent.
4000 to 4100 the window is 100% transparent to 100% opaque

note the word “window”. This feature is available for the pad background only and on the screen only (not on PostScript for instance).

:frowning: ok