Quote Originally Posted by Rony
I request developers of Ultimate-SEO to make it compatible with CSS3-Button addon, if possible.
As far as I know they are compatible. Just because two modules make changes to the same file does not mean the modules are not compatible. You will just need to look through the changes each module makes, see what is different, and then merge the changes together. As they do not modify the same functions in "html_output.php", installing both modules should be relatively easy using a file comparison or merge tool.

Quote Originally Posted by PearceStephens View Post
How do i tell in the affected files which bit of code to merge into my existing files??? Is there a comment anywhere informing me where to start and finish?
Good Question. WinMerge, BeyondCompare, and a number of other tools provide a side-by-side line-by-line comparison between two files indicating where the files are different, what is different, and allowing you to "merge" the code from one side to the other. These and similar tools are the fastest way to merge changes to any core "Zen Cart" files.

I would highly recommend installing and using one of these tools if you have made ANY changes to "Zen Cart". They are definitely time savers and have many other uses ;)

Why no comment such as "START USU" / "STOP USU" in those files? For the most part the changes made by this module are very minor and consist of only one block of code (I avoid changing core files or core database tables).

The only file with extensive changes is the 1.5.x "query_factory.php". This file was modified to provide more consistent output and address some bugs. The "query_factory.php" file in the distribution under consideration for inclusion in the next "Zen Cart" release. For Zen Cart 1.5.0 and 1.5.1 you should just override the old file with the file in the distribution of this module.