The `TGraph` copy constructor also copy the underlying `TH1F` if it exists (it...

The `TGraph` copy constructor also copy the underlying `TH1F` if it exists (it holds the axis titles).

README/ReleaseNotes/v610/index.md

@@ -173,7 +173,8 @@ The following interfaces have been removed, after deprecation in v6.08.
 - The "BOX" option, to draw 3D histograms, has been reimplemented by Evgueni Tcherniaev
   The following picture show the old and new version
 - `ChangeLabel` is now available for log axis as well as requested [here](https://sft.its.cern.ch/jira/browse/ROOT-8537).
-
+- The `TGraph` copy constructor also copy the underlying `TH1F` if it exists (it
+  holds the axis titles).
 
 ![New box option for 3D histograms](NewBoxOption.png)
 

hist/hist/src/TGraph.cxx

@@ -157,9 +157,6 @@ TGraph::TGraph(Int_t n, const Double_t *x, const Double_t *y)
 
 ////////////////////////////////////////////////////////////////////////////////
 /// Copy constructor for this graph
-///
-/// This copy constructor does not copy the underlying histogram. Basic informations
-/// attached to it (like axis titles) will be lost after a copy.
 
 TGraph::TGraph(const TGraph &gr)
    : TNamed(gr), TAttLine(gr), TAttFill(gr), TAttMarker(gr)
@@ -168,7 +165,8 @@ TGraph::TGraph(const TGraph &gr)
    fMaxSize = gr.fMaxSize;
    if (gr.fFunctions) fFunctions = (TList*)gr.fFunctions->Clone();
    else fFunctions = new TList;
-   fHistogram = 0;
+   if (gr.fHistogram) fHistogram = (TH1F*)gr.fHistogram->Clone();
+   else fHistogram = 0;
    fMinimum = gr.fMinimum;
    fMaximum = gr.fMaximum;
    if (!fMaxSize) {