Hi grprt, welcome to the forum.
I suggest you click on one of the tools - e.g., the magnifier - along the top of the Camera Raw dialog to make the application current and give it back the focus.
As for what might be stealing focus from Photoshop / Camera Raw... Anything else you have running on your system?
Do you really expect anyone to be able to help you without your having provided even basic system info? Do you have a Mac or PC? What OS version?
This morning, my cursor is working normally (giving me RGB readouts).
I only have this problem about 5% of the time. My computers are a MacPro, and I also have this problem on my MacBook Pro, both computers running Snow Leopard and both with CS6.
I have my magnifier permanently turned off in Bridge Preferences. Clicking on any of the Tools in the toolbar has no effect on the RGB readout. Most of the time, there's no problem with getting the RGB readout on either computer. I use and rely on this feature constantly.
My question is, what controls the cursor's ability to give an RGB readout, and especially why this is occasionally not available? I can't think of any other variables that differ when the readout is not available.
You're saying you can click the magnifying glass tool, see the cursor change to a magnifier yet not do the RGB readout? Or does it not change?
Unfortunately since you have a Mac I'm not an expert on that system and can't really help you with system-level stuff.
But it sure sounds to me like some other application (with possibly a hidden window?) has the focus instead of Photoshop / Camera Raw.
Thanks for trying to help. I'll have to wait until the problem reoccurs and check what else is running. I was hoping someone could tell me that some cursor preferences existed somewhere.
The cursor readout does not seem to be related to any tool; I get the RGB readout with any tool selected. When the RGB readout does not work, selecting other tools has no effect. The RGB readout seems to be related to the cursor, not a tool.
The next time this happens, I will try restarting the computer to see if that clears the condition.
It just happened again this evening. Cursor readout blackout. I restarted my Mac, now it's fine. Anyone have any ideas why this happens? Probably not a RAW issue.