I am not able to build the newest qwt 5.3.0 trunk on Windows XP.
On qwt 5.2.0 everting works fine.

I tried it from "Qt Creator":

qwt_plot_intervalcurve.obj:-1: error: Nicht aufgelöstes externes Symbol ""public: bool __thiscall QwtDoublePoint3D:perator==(class QwtDoublePoint3D const &)const " (??8QwtDoublePoint3D@@QBE_NABV0@@Z)".

and from the "VS-Command Prompt":

"C:\Programme\Microsoft Visual Studio 9.0\VC\BIN\nmake.exe" -f Makefile.
Debug all

Microsoft (R) Program Maintenance Utility, Version 9.00.21022.08
Copyright (C) Microsoft Corporation. Alle Rechte vorbehalten.

linking ..\lib\qwtd5.dll
Bibliothek "..\lib\qwtd5.lib" und Objekt "..\lib\qwtd5.exp" werden erstellt.
qwt_plot_intervalcurve.obj : error LNK2001: Nicht aufgelöstes externes Symbol ""
public: bool __thiscall QwtDoublePoint3D:perator==(class QwtDoublePoint3D cons
t &)const " (??8QwtDoublePoint3D@@QBE_NABV0@@Z)".
...

Thank for every help.