[JKT]

This is not a bug but a (extremely flawed, IMO) characteristic of the Input Manager system in OS X which is abused by developers of non-input manager software to hack applications. Anything that is installed as an input manager is loaded into every single application opened, no matter if it is relevant to that application or not, with obvious downsides to the stability of certain applications which can conflict with said input manager hacks. If anything, the ability to turn them off in OmniWeb (if it even works) is potentially a huge bonus.

In the case of the hacks you listed, they utilise SIMBL to do their dirty work.