Weird cursor behavior.

[Whitehill]

The cursor on my 10.8.2 iMac has started misbehaving. It changes from normal NW pointing arrow, to I-beam, to pointing finger, depending on where I move the cursor. Imagine the screen divided into 4 vertical stripes, numbered 1 to 4, left to right. With focus in the Finder, as I move the cursor into stripe #2, it changes from arrow to finger; when I move out to any other stripe, it goes back to an arrow.

In applications Mail and Safari, the changes seem to happen at random, with no special relation to position. It's about evenly split between arrow and finger, with I-beam now and then.

I use a Magic Mouse, but I get the same behavior with a wired USB mouse. I have not recently installed new hardware or software. The behavior started Saturday morning after my weekly restart. Today I performed a "safe" boot followed by another restart - no change. Then I booted to "recovery" and repaired permissions, twice. No change.

Any advice?

[DeltaMac]

Same response for me - the mouse cursor changes as I mouse over different areas. Mouse over a text area, and the cursor changes to an i-beam. Mouse over a weblink, and the cursor changes to pointing finger.
What you describe sounds normal?
You said the change appears random, with no relation to position.
Does the cursor change only when you move it? If so - it's related to position (and whatever "active" window it passes over)
Or, do you see the various cursor changes, even though your cursor is precisely in the same position?

Does the active app agree with the window that you mouse across when the cursor changes properly?
Active app will be the app name displayed in the menubar, next to the Apple menu.
That is, if you mouse across a TextEdit window, is TextEdit displayed in the menubar as the active app (or is it some other app name displayed in the menubar, such as Finder)?

[Whitehill]

It changes only when I move it. The active app is in agreement. In your (DeltaMac's) reply, consider the line

Does the active app agree with the window that you mouse across when the cursor changes

When I mouse on that line, starting in the whitespace on the right, the cursor is an arrow. As I move left, when I get to "changes", the cursor changes to I-beam; when I get to "that" is goes back to arrow; to "with", back to I-beam; to "agree", to finger all the way to the left end.

Moving in the other direction, it starts as a finger, to I-beam at "with", to arrow at "the" and to the right side.

[DeltaMac]

So, it consistently shows the same cursor changes in the same locations?
Not too random, then, is it?

Do you get the same result when logged in to another user account?

Try deleting this file from your user folder/Library/Preferences folder: com.apple.BezelServices.plist

[Whitehill]

Random in the sense that, if I move the Safari window to the left end of the screen, the sequence of changes I mentioned in my last post changes. Now ...

Logged in as Guest, the experiment behaves as I would expect. Starting at the right, it's an arrow. Moving left, when I hit text it changes to I-beam, and stays that way all the way to the left side of the window.

I deleted that file, and its associated lock file, but no changes. Should I restart?

[Whitehill]

I restarted, and ... it's gone! I would click "Thanks" right now, but I have an itch between my shoulder blades. What is that plist supposed to do?

[DeltaMac]

I don't think the guest user is too relevant here, as you can't try too much in changing settings (the guest account, and changes, are deleted when you log out of the guest user)
Do this in a real user account. Make a new, fresh user just for this purpose, and here's another reason why: You can make some changes to the settings, so you can go into your user/Library/Preferences to see which specific .plists are updated when you change settings. As your difficulty seems to be pointing to different areas of your screen (the screen itself responds, and not just the window for an app, which changes when YOU change the location of the window on the screen) then you need to find screen settings that are applied, regardless of an apps settings.
here's a few to try out (by deleting) in your normal user.
Log out, then log back in to your normal user after deleting a few of these:
com.apple.systemuiserver.plist
com.apple.preference.desktopscreeneffect.plist
com.apple.HIToolbox.plist
com.apple.BezelServices.plist

be sure to look in the Preferences/Byhost folder, too. You'll likely find some with those names there, too. You might see mostly the same named files, ending in .lockfile
I see no harm in also removing those.
Again, after removing those files, logout, log back in (or just restart)

Look again, if that DOESN'T change anything, for the com.apple.desktop files, or com.apple.finder files, or com.apple.systempreferences files.
It's challenging to pin this down in a simple "this is how to fix it in one easy step", as lots of the .plist files are interrelated - but I think that the systemuiserver files will likely do the trick... Let me know.

[DeltaMac]

You can do all that in my last post (but if the bezel services did it, I'm glad to hear that helped! )

the com.apple.BezelServices.plist file has settings for displaying and controlling screen elements. That's a little simplistic, I think - however, it provides the settings used by the system for properly defining the window edges (the bezels), so - that would be part of how the screen is presented, which, by inference, would define the areas for screen response to input devices, like the correct position for "grabbing" the edge of a window for dragging or resizing. It would follow that the position of the mouse has to be detected properly, and "BezelServices" is a primary point for that detection process.
And - deleting that .plist file, and restarting, would reset how the system sets up and defines screen elements.
I'm not sure if that's technically correct, but I think it's pretty close for your situation.