'dragRotation' is not loaded when loading a state file

[lukasvin]

When loading a state file, the 'dragRotation' property is reset.

steps to reproduce:

1. add any image layer
2. drag the sun and rotate it into any non-default position
3. save the state
4. load the saved state

The dragged rotation is reset to the default position [1,0,0,0].

[bogdanni]

Restoring state involves resetting the viewpoint which leads to reset of "dragRotation".
I need to see why the last step was necessary, thanks.