get_size
Description:
This function tries to "do what you mean" and return the size an actor will have.
If the actor has a valid allocation, the allocation will be returned; otherwise, the actors natural size request will be returned.
If you care whether you get the request vs. the allocation, you should probably call a different function like get_allocation_box or get_preferred_width.
Parameters:
| this | A Actor | 
| width | return location for the width, or  | 
| height | return location for the height, or  |