drawing drop down arrows with stylesheets?

Sometimes the position of the arrows in QTreeWidgets is not suitable, due to the size of the images used instead of the arrows, or for other aesthetic reasons.

It would be nice if stylesheet code like this was supported:

setStyleSheet(
"QTreeWidget

{" "background-color: #fafafa;" "}

"
"QTreeView::branch:open:

{" "margin-left: 10px;" "margin-right: 5px;" "}

"
"QTreeView::branch:closed:

{" "margin-left: 10px;" "margin-right: 5px;" "}

"
);