Snapshot the a child of this.
When a widget receives a call to the snapshot function, it must send synthetic [[email protected]] calls to all children. This
function provides a convenient way of doing this. A widget, when it receives a call to its [[email protected]] function, calls
snapshot_child once for each child, passing in the snapshot the widget received.
snapshot_child takes care of translating the origin of snapshot, and deciding whether the child
needs to be snapshot.
This function does nothing for children that implement `GtkNative`.
| this |
a `GtkWidget` |
| child |
a child of this |
| snapshot |
`GtkSnapshot` as passed to the widget. In particular, no calls to translate or other transform calls should have been made. |