Describes how existing data is combined with new data when using property_change.
Value | Symbolic name | Description |
| 0 | Gdk::PROP_MODE_REPLACE | The new data replaces the existing data. |
| 1 | Gdk::PROP_MODE_PREPEND | The new data is prepended to the existing data. |
| 2 | Gdk::PROP_MODE_APPEND | The new data is appended to the existing data. |