yesterday(Nov 17, 2010), I received a requirement email from my Batch ReaderEnable customer,

I contacted you for a advise on PDF compare. we do have a requirement to Comparing the version of PDF files, when we are using Acrobat inbuilt compare options, it’s comparing only the text and it’ll miss out the formatting elements (bold, italic, superscript, subscript, bolditalic etc), it caused lot off manual work and time consuming, do you have any idea or software for this, if so please inform us, we will discuss the cost.

and I occurred to DiffPDF, a Free open source and cross-platform software that can compare two PDF in text and appearance mode. it is developed in Qt and bases on Poppler-qt.

P.S.
I has recommend it to PortableApps.com, and hope it can be accepted.

DiffPDF is developed by Mark Summerfield, I just compiled it to windows 32 version.
DiffPDF depends on poppler, poppler-qt, Qt4 library.

DiffPDF can compare two PDF files. It offers two comparison modes: Text and Appearance.
By default the comparison is of the text on each pair of pages, but comparing the appearance of pages is also supported (for example, if a diagram is changed or if a paragraph is reformatted). It is also possible to compare particular pages or page ranges. For example, if there are two versions of a PDF file, one with pages 1-12 and the other with pages 1-13 because of an extra page having been added as page 4, they can be compared by specifying two page ranges, 1-12 for the first and 1-3, 5-13 for the second. This will make DiffPDF compare pages in the pairs (1, 1), (2, 2), (3, 3), (4, 5), (5, 6), and so on, to (12, 13).

It is open source(of course free software), want to try it on your windows XP/Windows 7, please download here.

I compiled a static Qt4 application(fancybrowser) under Ubuntu 10.04, it works under Ubuntu 10.04, but when I tried to run it under CentOS 4.6.2, I got the following error,

./fancybrowser: /lib/tls/libc.so.6: version `GLIBC_2.4' not found (required by ./fancybrowser)

After some research, I knew I have to compile it under CentOS 4.6.2 and lower version, or under Debian 4, so I install Debian 4 under vmware, recompile Qt under Debian4, compile fancybrowser, there are many duplicated job.
continuing search, and I got the suggestion,
Try the linux-lsb-g++ mkspec if you intend to deploy a Qt application in several different Linux systems/distros.

P.S.
What is the LSB?
LSB means Linux Standard Base.

An operating system’s success is inextricably linked with the number and quality of applications that run on top of it. Linux and its variances between distributions, however, present ISVs and individual developers with a unique set of challenges: different distributions of Linux make use of different versions of libraries, important files stored in different locations, and so on. If an ISV wants to reach a global Linux audience, they must support more than one distribution of Linux. These challenges and variances make it difficult–and costly–for ISVs to target the Linux platform.

The Linux Standard Base was created to solve these challenges and lower the overall costs of supporting the Linux platform. By reducing the differences between individual Linux distributions, the LSB greatly reduces the costs involved with porting applications to different distributions, as well as lowers the cost and effort involved in after-market support of those applications.