I assume movement tracking will not be added because there are other programs available which are able to do it and there are just other necessary features which have a higher priority.
Therefore, for simple tracking of the position, keyframing of filters can be used to achieve something similar. Now, the Mask: Simple Shape filter has the option to use the position keyframing but the values have to be changed manually. By contrast, the Size and Position filter has a handle which makes the keyframing process way easier. So something similar would be alleviating.
It is actually possible to use the Size and Position filter in following order:
- Mask: Simple shape
- Size and Position
- Mask: Apply
With this using the keyframing of the Size and Position filter, [Filter] is applied but that is only useful for objects like blurred number plates, so if there is no background in the affected area. Though, a handle would still be easier.
I do not know if this is tricky to implement but since there is already one implementation, I thought suggesting this is not a too difficult task. But please, correct me if I’m wrong.