Shedding some light on ActiveX
"IE users can enjoy animation, 3-dimensional rendering, and dynamic scripting; but apart from Microsoft's web applications, this has been used much less frequently, largely because ActiveX has proven itself open to many security holes."
The bottom line on usability:
Don't use it unless you want to cater to just Windows and IE users. That's a large percentage of the people out there, so maybe that's what you want to do. Use with extreme caution.
More on Usability:
Christian Wagner (who, like myself, has his site lisenced with Creative Commons) has the following summary of ActiveX installation in Internet Exploder...er, Explorer.
Without XP SP2 the ActiveX install looks like
With Windows XP Service Pack 2, you see this notification bar at the top of Internet Explorer instead:
If you click on the notification bar and tell it to download the control, you receive one more prompt:
Wagner chose Cult3D "as an example because it sounds malicious, but is actually benign." Wagner suggests you "be paranoid and be informed" but I think being informed and judicious is a loftier goal. Certainly, if you aren't informed, you should be paranoid.
C|net lists "no ActiveX support" as "The bad" in their review of Mozilla Firefox, but it's worth noting that the c|net review was not a review of Firefox 2.0, but of 1.0. Firefox still does not natively support ActiveX in 2.0.
"It is generally believed that ActiveX is inherently insecure compared to the NPAPI plug-in system, but this is only partially true. ActiveX controls and plug-ins have all the same powers over the computer as each other, so a malicious plug-in can do just as much damage as an ActiveX control. But by the way ActiveX is implemented in Internet Explorer (and its use in many other Microsoft applications), it is easier to get a malicious ActiveX Control onto a user's computer and to get it to run. A detailed explanation can be found here: http://en.wikipedia.org/wiki/NPAPI#Security" - MozillaZine
MozillaZine has a conflict of interest, but they do point out that plugins have the "same" security risks as ActiveX controls. ActiveX also is Windows specific, which gets into usabiliy across operating systems. While Windows continues to dominate the market, Linux, BSD, Solaris and OS X all still exist.
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