Emitted when a drag is about to be initiated.
It returns the `GdkContentProvider` to use for the drag that is about to start. The default handler for this signal returns the value of the [[email protected]:content] property, so if you set up that property ahead of time, you don't need to connect to this signal.
| x |
the X coordinate of the drag starting point |
| y |
the Y coordinate fo the drag starting point |
|
a `GdkContentProvider` |