Gets the contents of this stored in value.
The value will have been initialized to the `GType` the value should be provided in. This given `GType` does not need to be
listed in the formats returned by [method@Gdk.ContentProvider.ref_formats]. However, if the given `GType` is not supported, this operation
can fail and `G_IO_ERROR_NOT_SUPPORTED` will be reported.
| this |
a `GdkContentProvider` |
| value |
the `GValue` to fill |
|
true if the value was set successfully. Otherwise throws will be set to describe the failure. |