Bug in AnimationController?

[ElanPlus2]

Hi

This is my first post here. I have tried searching the web to see if my problem is already reported, maybe my problem is related to https://bugreports.qt-project.org/browse/QTBUG-25967 ?

I've been trying to do some "accordion style page swiping stuff". As a starting point I used the Qt calqlatr demo and the AnimationController for inspiration.

During my development I noticed that while dragging pages, the AnimationController animation would flicker and for a tiny moment the animation would display my page either at the start or end position and then jump back to the positon I expected.

I added debug printouts to see what the AnimationController's progress value was before I updated it, what my intended new value was, then I set the progress value and immediately after read back the current value.

It turns out that what I was seeing visually was also reflected in the progress value. Suddenly it would jump to 0 or 1 and then return to the value I had assigned.

The problem is visible also in the calqlatr demo, if I just do some vigorous mouse movents trying to shift the position of the pages they will flicker.

I'm using Qt 5.1.1 (Qt 5.1.1 for Windows 32-bit (MinGW 4.8, OpenGL, 666 MB)) from the downloads page.

Has anyone else seen this?

Thanks in advance,
Pär-Olof Håkansson