get_axes
Description:
Extracts all axis values from an event.
To find out which axes are used, use [method@Gdk.DeviceTool.get_axes] on the device tool returned by [method@Gdk.Event.get_device_tool].
Parameters:
| this | a `GdkEvent` | 
| axes | the array of values for all axes | 
| n_axes | the length of array | 
Returns:
| true on success, otherwise false |