Adobe is suing its arch-rival Macromedia for infringement of intellectual property, specifically its patented tabbed palette interface elements. Adobe claims that it invented this "key user interface element and method" and incorporated into it into its products before Macromedia.

Several of Adobe’s main products clash with those of Macromedia. Adobe’s vector-drawing application Illustrator competes with Macromedia FreeHand, its WYSIWYG Web editor GoLive with Macromedia’s Dreamweaver, and its LiveMotion animated Web graphics program LiveMotion with Flash. Other competing products include Adobe’s ImageReady (tabs pictured top right) and Macromedia’s FireWorks (above bottom right) Web-graphics apps.

Macromedia denials Macromedia has to file a response within 20 days, or ask for an extension. It is not unusual for cases like these to take several years to resolve, Adobe admits.

Not surprisingly, Macromedia has issued a statement "categorically denying the claims made in the lawsuit Adobe filed over patent infringement."

"We believe the claims made are without merit and that the patent was invalid because it was obtained by not disclosing relevant prior art," which is previous work of the same type, according to Macromedia.

Macromedia says it told Adobe that the patent was invalid back in 1996, when Adobe representatives first contacted Macromedia with complaints of infringement. The company says it repeated its position when Adobe most recently contacted Macromedia about the patent in May of 1999. The patent in question is US Patent No. 5,546,528, granted to Adobe in August of 1996. No hearing has yet been set.

Smokin' tabs US Patent No. 5,546,528 (in the District Court of Delaware) covers the tabbed palette patent, which is Adobe's method of displaying and working with multiple sets of information in the same area of the computer screen. The patented invention allows users to customize how the functions in the product are organized on the workspace.

Adobe claims that "these elements are heavily associated with the Adobe brand; they are a major competitive advantage and a significant reason why customers purchase our products."

"We are taking this action now, after notifying Macromedia on several occasions that its products are infringing our patent. The remedy sought is straightforward - we ask them to stop infringing," said Bruce Chizen, Adobe's president.

Brand attack "Adobe will not be the R&D department for its competitors. Our patent and other aspects of our user interface are key to the user experience and functionality of our products; they are essential to differentiate our products and brand from others," he added.

"Adobe will aggressively enforce its patent portfolio and protect the interests of its stockholders," said Colleen Pouliot, Adobe's senior vice president and general counsel. "To be fair, competition has to be based on a level playing field - companies must compete on the basis of innovation and according to the laws of the land. All we ask is that Macromedia play by these rules and stop infringing our patent."

No choice An FAQ on Adobe’s Web site claims that it is taking this action as "a last resort".

"Adobe first contacted Macromedia in 1996 and several times thereafter. We warned Macromedia repeatedly, but it ignored those warnings. We do not commonly litigate, but this instance with Macromedia is flagrant, and involves a pattern of violations as well as public statements that indicate its intent to continue to infringe our patent. Macromedia infringes our patent across its product line. Macromedia is copying the Adobe UI and calling it their own", the statement reads.

"We had hoped to keep this matter out of the courts but recent events have given us no choice."

The same statement says that Macromedia has put its customers "at risk at having to reinvest in learning their products".

"Like Velcro and Post-It notes, the very best inventions become so familiar that they are taken for granted. The fact that tabbed palettes seem so natural and common now is a testimony to the Adobe development effort that went into the invention," the company claims.

Keep reading Macworld’s Daily News for updates.