It all started as a small feature request - Adding style sheet support for Item views. I quickly found out that our default delegate, QItemDelegate, doesn’t use QStyle the way it is supposed to. Jens had faced the same problem when trying to provide native look and feel for Vista and ended up writing his own delegate. This is quite a limitation because currently authors of custom QStyles can customize the look of everything in Qt except item views.
So was born QStyledItemDelegate - The default delegate for Item views starting 4.4. To let that sink in - all our views now delegate painting to QStyledItemDelegate instead of QItemDelegate. QStyledItemDelegate prompty plays its part by delegating everything to QStyle 
The cool thing is that this delegate uses the QStyle to determine the sizeHint, the layout of the text, indicators and icon. And of course, it paints everything through QStyle. Complete control to QStyle.
Jens has already incorporated this new feature into QWindowsVistaStyle. So, by default, your views will look all fancy in 4.4 like below:
We are unsure about how selection in table view must be handled. We are open to suggestions:
On other platforms, they should exactly like before. If you had written your own delegate using QItemDelegate, it is completely unaffected by this change. If having to write a custom QStyle or a custom delegate sounds daunting, just use style sheets. Try something like this,
QTreeView::item {
border: 1px solid #d9d9d9;
border-top-color: transparent;
border-bottom-color: transparent;
}
QTreeView::item:hover {
background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, stop: 0 #e7effd, stop: 1 #cbdaf1);
border: 1px solid #bfcde4;
}
QTreeView::item:selected {
border: 1px solid #567dbc;
}
QTreeView::item:selected:active{
background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, stop: 0 #6ea1f1, stop: 1 #567dbc);
}
QTreeView::item:selected:!active {
background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, stop: 0 #6b9be8, stop: 1 #577fbf);
}
Here’s how it looks:
See Customizing QTreeView, Customizing QListView for more information.
We merged the new delegate into our main branch last week, so if use the latest snapshots, you already have it. If you have any specific requirements to styling of tree widgets, list views and tables in mind and are wondering if it is possible now using the new delegate, please leave behind a note!
