public unowned DeviceTool? get_device_tool ()
Returns a `GdkDeviceTool` representing the tool that caused the event.
If the was not generated by a device that supports different tools (such as a tablet), this function will return null.
Note: the `GdkDeviceTool` will be constant during the application lifetime, if settings must be stored persistently across runs, see [ method@Gdk.DeviceTool.get_serial].
The current device tool