Qt StyleSheet for a QTreeView - c++

Question

I'm currently facing a problem about stylesheets of Qt and QTreeView.
I simply want the current item selected in the tree to be written in bold.
I did research before and the solutions given in many forums are:
myView->setStyleSheet("QTreeView::item:selected {font: bold;}");
But this doesn't work for me. I tried QTreeView {font: bold;} which works (for every item) and QTreeView::item:selected {background-color:red;} works too. Why is font not working for the selected item ?
Thanks !

Answer 1

Pretty old question but maybe someone will find it useful.
I am having the same problems using Qt 5.3.
I found some info on qt-center that it cannot be done by stylesheet.
Is there a way to change the font-weight (or font-size minimum) of the
selected item in QListWidget? No, as such font style option applies
to QWidgets, so you could apply the font (or other like font-size)
style option to the entire QWidget (QListWidget in this case) and not
to special behavior of a derived QWidget i.e. QListWidget's selection
item.
I think that it applies also to QTreeView, because I was not able to change its style as well.
I can change border, color, background color but nothing regarding font.
First I thought that I have to reimplement paintEvent function because I am reimplementing QTreeView. This didn't work as well.
Workaround solution:
But I found some workaround using QStyledItemDelegate.
Basically you have to subclass QTreeView, then subclass QStyledItemDelegate.
Maybe it would work without subclassing QTreeView, but you have to somehow catch some signal with selected and deselected items and call setItemDelegateForRow and setItemDelegateForColumn (it should change only intersecting cell)
Reimplement QStyledItemDelegate::paint in this way:
QStyledItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
QStyleOptionViewItemV4 editedOpt = option;
editedOpt.font = QFont("Arial", 23, 500);
initStyleOption( &editedOpt, index );
QStyledItemDelegate::paint(painter, editedOpt, index);
}
Reimplement QTreeView::selectionChanged(or plain QTreeView and catch QItemSelectionModel::selectionChanged) :
void CustomTreeView::selectionChanged(const QItemSelection &selected, const QItemSelection &deselected)
{
foreach(const QModelIndex &index, selected.indexes()) {
setItemDelegateForRow(index.row(), new CustomDelegate(this));
setItemDelegateForColumn(index.column(), new CustomDelegate(this));
}
foreach(const QModelIndex &index, deselected.indexes()) {
setItemDelegateForRow(index.row(), new QStyledItemDelegate(this));
setItemDelegateForColumn(index.column(), new QStyledItemDelegate(this));
}
}