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The recently released Safari 3.2 and 3.2.1 updates have triggered a spate of complaints, claiming that the new versions are crashing all the time. While there may be multiple causes for this symptom, there is one cause that likely accounts for the vast majority of the complaints: Safari add-ons, most especially Input Managers. These include PithHelmet/SIMBL and AcidSearch. This is not new to Safari 3.2.x. A similar precipitation of crashes was reported immediately after updating to earlier versions of Safari.
As noted in this Apple document on the Cocoa Application Framework: "The automatic loading of bundles located in InputManagers folders is now officially unsupported. The conditions for valid input manager bundle is further tightened. This functionality is likely to be disabled in a future release."
In other words, Input Managers are on the way out. And, while they may still work for now, don't count on things to go smoothly. In particular, when Apple updates Safari, it pays little or no attention to whether the update may break the ability of existing Input Managers to work. Often, a Safari update and installed Input Managers conflict, with Safari crashing as a result.
The immediate fix is to remove the problem Input Manager from your Library/InputManagers folder. With luck, the developer of the Input Manager software will release an update that is compatible with the latest Safari version. One such update already exists for PithHelmet and Safari 3.2. The best long-term solution is to give up on Input Managers altogether, instead of waiting for them to become extinct in the next version of Mac OS X.
Read article at Macworld.com