Regression Qt Designer in Qt 4.8.5 | Wrong dialog size + cannot resize anymore (grid layout is involved)

I found a strange issue with Qt Designer in Qt 4.8.5:

My goal is to edit an existing UI file, containing a grid layout. The problem is: As soon as I insert another "row" into the layout and, after that, resize the dialog, then the dialog will become much wider all of a sudden. And it can NOT be resized back to the proper size. Appears like as if the Minimum size has been locked to a much too big value.

See attachment for screenshots of how it looks before and afterwards.

Note that adding another row obviously is the cause of the problem, but it will not be triggered until I resize the dialog - and if it's only be a single pixel! Before adding the new row, it will resize just fine, without strange behavior. But: Any resize after the insertion and the dialog becomes much wider all of a sudden.

Also note: Problem does NOT exist in Qt Designer 4.8.4. And, if I edit the UI file in Qt 4.8.4, the resulting UI file will also work correctly in Qt 4.8.5. Seems like a regression to me.

Example UI file is here:
http://pastie.org/private/2w6pjccsvfmgnzhiwmogea

Regards,
MuldeR