TPad.h reads:
.. snip ...
Float_t fXlowNDC; //X bottom left corner of pad in NDC [0,1]
Float_t fYlowNDC; //Y bottom left corner of pad in NDC [0,1]
Float_t fWNDC; //Width of pad along X in NDC
Float_t fHNDC; //Height of pad along Y in NDC
Float_t fUxmin; //Minimum value on the X axis
Float_t fUymin; //Minimum value on the Y axis
Float_t fUxmax; //Maximum value on the X axis
Float_t fUymax; //Maximum value on the Y axis
... snip...
Float_t GetXlowNDC() {return fXlowNDC;}
Float_t GetYlowNDC() {return fYlowNDC;}
.... snip
Float_t GetUxmin() {return fUxmin;}
Float_t GetUymin() {return fUymin;}
Float_t GetUxmax() {return fUxmax;}
Float_t GetUymax() {return fUymax;}
I guess this is what you are looking for... - regards, pasha