The section for TPad::DrawFrame https://root.cern.ch/root/html/TPad.html#TPad:DrawFrame does not make it clear how to set axis labels. I had to actually read the source code to figure out that it uses a TH1 constructor with the title;xlabel;ylabel syntax in the last argument:
https://root.cern.ch/root/html/TH1.html#TH1:TH1
Could some text be added to clarify this for TPad::DrawFrame? Something like:
Jean-François