This issue has been driving me nuts lately, and I just now figured out what is going on. I'm using v5.0 (eval) right now, but I know this happens in v4.0 (registered) as well.

Steps to recreate:

1. Do a "Search in Files" on a project
   
2. Open a file that contains more than one instance of the searched term by double-clicking on the listing in the Log area
   
3. Press the F3 key to jump to the next instance of the search term

On the tab for the file, next to the File's name, it will be marked with an asterisk indicating that the file has been changed. Yet, nothing in the file has really changed. Usually, you can go to the Edit menu, and Undo and it will get rid of the asterisk (even though it doesnt really undo anything). However, I have had a couple of times when Undo wasnt available.

This is a problem (at least for me) because I am usually running three screens. It is VERY possible for me to be interrupted in the middle of looking through the search results and respond to the interruption. It's also possible that I alt+Tab to the wrong screen and start typing. So now I'm not sure if I have accidentally typed something into my php file or not. Before I figured out what was going on, I was pulling my hair out trying to find WHAT in the file had changed.

I've also seen it do a similar thing if you double-click on a word (to highlight it) and then single-click somewhere else in the file. The IDE marks the file as having changed, when nothing really has changed. However, it's not consistent; sometimes it marks it changed, sometimes it doesnt. I mention it because it would seem that there is something with highlighting words and then coming off that word that makes the IDE think something has changed.

Anyway, just wanted to make you aware of the "problem".

Just installed the registered version of 5.0 (build 5025) and was able to replicate the problem.

try turning og optimal fill and/or smart tabs. they probably parse the file again when it gets selected.

looks like Optimal Fill is the culprit. Once I turned that off, I am no longer able to replicate the problem. Now the question is: is it more convenient to have optimal fill on, and just now that this issue might arise, or leave it off so this issue doesnt happen at all?

I've always had Optimal Fill on. I guess I'll leave it off and see if I even notice a difference in the way the IDE behaves.

Thanks stappel for the tip!