I just setup dual monitors for my Mac and keep accidentally typing into an app in monitor 1 after I've moved my mouse to an app in monitor 2. I can't be the only one who runs into this with dual monitors so any advice for how to handle this?
Just make sure you remember to activate the text area you want to type in by clicking on it first, condition yourself to be aware of what is active.
This seems to crop up since scrolling works with out having to click on the window / content, and I think this leads us into a confused state that we have activated the app / window by placing the cursor over it and scrolling.
However that is not the case since scrolling a window by just mouse-ing over does not change which program was originally active. And to enter text or do other command actions that still requires that you tell Mac OS where your intending your input to go other wise it remembers the last active place selected.
And actually for other OS's this is a feature, called focus follow pointer or mouse but unfortunatly is not really implemented at a system wide level on OS X according to comments and feedback noted here Focus-follows-mouse (plus auto-raise) on Mac OS X. So it is not something you can easily enable in system preferences, and as far as I can tell no 3rd party App exist to add this functionality to OS X.
There are some
The way I handle this is that I treat the second monitor as more or less read-only. I move windows over there that I want to read but only interact with windows on the main screen. If I want to work with a window that's on the second screen I just move it to the first screen first.
Alternately, I use exposé and swap between entire spaces.