What the style order for use ? Like this ?

Example for QTreeView..

+-------------------------+
| StyleSheet |
+-------------------------+
| Delegate |
+-------------------------+
| Role from Model |
+-------------------------+
| QStyle |
+-------------------------+


So if I want make a custom background color for a QTreeView, and I use custom QStyle and Stylesheet. Then background color from stylesheet will be apply ? And background color from custom QStyle will be ignored ?