Weird issue with QProgressBar

[Djeezus]

Hello everyone,

I'm currently having a very weird issue with QProgressBar when displaying then in "busy mode" (when maximum and minimum are set to 0). Sometimes the bar will stay at the beginning of the and act kind of like a normal progress bar that stops after a very short distance (kinda hard to describe) and resets continually. The normal comportment would be of a fixed length and would move along the progress bar continually. After many tests and looking at the code for a long time, I haven't been able to isolate a cause (either from Qt or somewhere in my code). There are two elements to know though about this problem:

1. It only happens on linux, and on a very specific distribution of linux (we are using a custom version made with linuxfromscratch). The bug is not reproduced on XFCE, for example.
2. The Qt version used is 4.8.0. It is not an option to upgrade the Qt version at this time because it requires tons of work. The immediate goal is either to fix the bug or to find a workaround.

My question is basically : is there a known bug that causes this type of behaviour? I know there were issues with the progress bar in Qt 4.7 but this seems to have been fixed. I have also seen some forum posts about similar issues but there doesn't seem to be any bug on this on the bugtracker.

Thanks