Library view shows at least four items in a row

1. Open a qml file.
2. Switch to Design mode.
3. Change the width of the Library view.
   If it grows, it will display more and more items in one row. If it shrinks, though, it will always show at least four items in the same row. The resulting need for horizontal scrolling is inconvenient.

The number of items in a row of the Library view should be reduced when there's no sufficient space to display them.