Project: QGIS
Version: 2.8.0
The user interface for data defined symbology settings has been improved - moving the data defined option next to each data definable property (in keeping with other parts of QGIS such as the labeling properties). Also many new properties have been made data definable for symbology. This user interface improvement also provides a way to immediately see if a data defined override is defined as well as easier access to the data-defined settings.
