Odd random color font highliting

[Johnny-Don]

So this started about a month ago, the latest update didn’t fix it. Anyone have any thoughts? Late 2009 iMac i5. Clicks anywhere on the monitor seem to change the color or location of the odd higgliting. It is not app specific. The system fonts at the top of open programs will do it as well.

 

[bplein]

Almost looks like when you drag/select, as if your mouse is mistakenly sending signals that a mouse button is pushed when it is not.

But if that were the case, lots of other weird stuff would be going on too. It would not be usable.

 

[AphoticD]

I’ve also witnessed this in some window title bars on my late 2009 iMac 21.5” with High Sierra 10.13.2. I thought it could be the GeForce 9400 giving me trouble or just the specific app(s). Maybe installing the Nvidia web driver will solve this? I’ll give it a go when I get back to it.