http://patentsobserver.com/public/company/show?company=Altium+Ltd
thanks GeoffS, but "System for designing re-programmable digital hardware platforms" is quite general. i believe there are many system like this? but it is as general as "System for drawing a straight line on a computer monitor". i dont see any link to more detailed explanation of the system.
I don't think designing in similar functionality is a problem, provided you don't use any techniques that Altium may consider proprietary.
Look and feel i..e similar or identical interfaces might be more of an issue.
yes, similarities in GUI is very obvious and easy to avoid. but the "functionalities" or "technologies" is not so obvious. such as:
1) is grouping several schematics, pcb, libs in one project file patentable? or patented?
2) is functionality to be able to insert/import enclosure's 3D model into pcb 3D file or data for clearance checking patented?
3) mcu programming (IDE), compiling, debugging and testing it on the related PCB circuit (the IDE is built in the EDA). can anybody do it? or just Altium has the right?
and many others relating functionalities. i think it sounds stupid if one can patent the 3 examples above but who knows? someone said you can patent air if you have the money. and you cannot design a round corner handphone Apple will sue you.

@KJDS. yes i know possibly each country has they own patent service site and searchable, i only ask if someone aware of patents owned by Altium and can provide the numbers quickly. otherwise i'll just sweep the whole internet when my connection speed is max. thanks
They also hold copyright over the look and feel of the software, so if it comes out looking the same you're in trouble.
but then, what criteria to judge it as the "same", without specific description then we are blind. if another software has only different color, will it avoid patent infringment?
@Marco: ditto! the rounded corner! will be interesting if someone has the patent number, but that is another OT.
ps: i googled earlier just to read a "patent infringement case" by Altium vs Uniloc. but as i read it through the middle of the text just to realize its a different Altium based in USA developing distributed licenses server based system sigh. my connection is not so good now will search later.