XCode immediately show filecontent on click

I'm new to XCode. I use XCode 3.1.3. In my project, i have on the left side the list of my project files, on the right side there is a textwindow showing code, and on top there's another small field showing some info about the file.

At first, when i clicked in the left list on a file, the file content immediately showed up in the textfield on the right side. However - now i changed something (but i don't know what) and now the field does not anymore automatically show the content of the file. if i double click on the file in the list, a new window opens showin开发者_JS百科g the code - i'd like to get back the initial behaviour.

how can I set this?

I think you're referring to "All-In-One" Layout (changeable in XCode -> Preferences -> General). Mind you - if you want to change layout - you must have all projects closed.

Did you relaunch Xcode? I saw the bug when showing file content just stopped working, but relaunching Xcode always fixed it.