* Apple sued Microsoft back in the day for stealing the look and feel of Mac OS, and failed. So that argument can be very hard to make.
Illegal copying can occur by exact copying of source or object code or by paraphrasing (misappropriating a program's structure or architecture, its inter-modular relationships, and/or its algorithms and data structures, at least insofar as these elements do not constitute unprotectable ideas - this can occur by copying the fundamental essence or structure of a copyrighted work even while rephrasing or restating it in immaterial respects).
Impermissible copying can also involve exact duplication of a user interface, or a "paraphrasing" of that interface (e.g., by creating screen displays and menu commands which are very similar but not identical to those of a copyrighted program).
Though interface elements can potentially be copyrighted, the advice you give is sound in most cases because of the courts' reluctance to give any party a monopoly on interface ideas in the guise of copyright (thus, Apple had sought unsuccessfully via copyright to gain exclusive use of a variety of interface elements, such as a visual depiction of a trash can). This is where "look and feel" cases become so difficult - who wants to give anybody exclusive rights via copyright, for example, to the basic ideas behind a spreadsheet? That is why many of those older cases failed.
In spite of this, I don't know that I would simply dismiss the look-and-feel aspect of this case based on the interface involved here. On its face, there appears to be more involved with this interface than mere ideas and, when there are creative forms of expression involved, and the copying is exact or so significantly "paraphrased" as to be almost indistinguishable, an interface infringement may have occurred.
All of the above, however, is based on a U.S. law analysis and may be irrelevant (at least legally) in China. If there is some way to bring U.S. legal principles into play, or anything analogous to them, then this would appear to be a fairly flagrant instance of illegal copying. While the costs of launching and pursuing a formal legal fight would be great, as long as you have a reasonable venue in which to launch it (i.e., one that respects IP rights) and the resources to carry it through to the preliminary injunction stage (usually 6 to 8 weeks into the case), winning a preliminary injunction would likely work its effect in causing Microsoft to fold, assuming it otherwise is willing before that to fight and is able to survive a horrible onslaught of bad publicity.
But simply cloning a user interface is legal, at least in US case law.
Can you give us citation that it is legal, or are making your claim based on the above lawsuits?
Having a look and feel that is "similar" but "not the same" is open to debate, but having 90% of the interface ripped off, pixel by pixel can't be just "ok". We don't know that because something so dumb didn't happen before in the highest level.
>None of the source code or machine code that generated the menus was copied, but the names of the commands and the organization of those commands into a hierarchy were virtually identical.
From: http://en.wikipedia.org/wiki/Lotus_Dev._Corp._v._Borland_Int...
In this case MS not only copied the interface of plurk, but from the look of it they also stole the code. Such a blatant copyright infringement has never happened before at this level to the best of my knowledge.
Your claim that it is "legal to copy UI in US law", based on the above example, is false.
Copying a menu, its command name and hierarchy is not the same as copying an interface. A menu is only small sub-set of user interface.
But that's just how it is in the design industry -- new designs come out quickly, so it's usually not worth the effort to fight knockoffs.
That's because design is an area covered by trademark, not copyright. You can trademark a design if it's distinctive or innovative enough, at least in the U.S., and have protection from imitation. You don't even have to register a trademark to establish rights, you can declare your rights simply by using the (TM) symbol, although you do have to register in order to defend the rights in federal court or claim international protection.
http://www.uspto.gov/trademarks/basics/register.jsp
From a whois check on their domain name, however, Plurk Inc. appears to be Canadian. Anyone have details on the what differences there are in the Canadian trademark system?