Qt 4.7 and 4.8 Bug Fix Highlights, including for ItemView performance problems
Phil, 3-6-2012

4.7.0

- QList
* Added reserve() function
* Various performance improvements

- QGraphicsItem
* [QTBUG-9024] Improved performance when calling update() on items that are clipped by an ancestor (QGraphicsItem::ItemClipsChildrenToShape).
* [QTBUG-7703], [QTBUG-8378] Fixed scrolling issues

- QGraphicsView
* [QTBUG-7438] Fixed viewport cursor getting reset when releasing the mouse.
* [QTBUG-10338] Fixed drawing artifacts due to rounding errors.

... searching bug reports:

• QtBug-8886: Low performance of changing data in a densely populated QTreeView ... addressed in 4.7.0
  ... note from Phil: I saw this during the development of the Mass Balance Summary multiple-level treeview. I ended up storing selection and open/closed states in my own internal data and resetting the entire model when I was doing high-level multiple item Open/Close tree operations.
   
• QtBug-884: Selecting a lot of rows one at a time can cause a performance problem ... addressed in 4.7.0
  ... note from Phil: I sometimes restore an arbitrary saved selection when rebuilding the model (which is often done rather casually as a work around for known performance problems, e.g. as a work-around for prior bug scenario).

4.7.1

- QGraphicsScene
* [QT-3674] Spurious assert triggered from render().

- QTreeView
* [QTBUG-13567] Do not scroll to top if last item is removed.

- QtXml
* Fixed a crash when parsing invalid tag names.

4.7.2

- QTableWidget
* [QTBUG-15973] Resizing a QTableWidget column where a cell contains a QProgressBar made it crash.

4.7.3

(nothing notable in this patch release).

UNSOLVED:

• QTBUG-10712: QTreeWidget sorts unrelated items leading to horrible performance

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