Here's the final set of steps:
1. Open CodeBlocks and create new file (File -> New).
2. Minimize CodeBlocks using taskbar icon. If you minimize using the minimize button in the top of the window the bug cannot be reproduced.
3. Open the new file in external editor (such as Notepad).
4. Edit the file in Notepad and save changes you made.
5. Press the CodeBlocks button in the Taskbar to maximize CodeBlocks. Do not restore by right clicking with mouse and selecting Restore.
6. The file is changed but no reload file dialog is shown.
Now try to regain focus to the main application (first lose the focus and then set the focus back) and the reload file dialog is displayed. This can be done e.g. by minimizing C::B.
If it's still unclear what I'm talking about, watch this flash demo, it shows the steps and reproduces the bug:
http://ajonsson.kapsi.fi/pub/bug.htm. It's made with
Wink. I know the colors look like s***t but I needed to keep the file size small. Now I'm going to bed. Good night.