When you build a mesh/model and use the 'rotate model' tool, the rotate widget is initially aligned to the 'world' coordinate system which coincides with the 'model' coordinate system.
If you then use the rotate model tool widget, it stays aligned with the model: rotating the widget rotates the model, as you would expect.
It would be useful to be able to reset the widget's rotation to coincide with the 'world' coordinate system without resetting the rotation of the model.
For example, i might use the rotate tool to get my model approximately aligned with Z up and X and Y pointing where i want, but to then make fine adjustments in only one axis i can no longer use the red/green/blue XYZ rings on the widget because they have all been rotated away from the world axes, remaining aligned with the model's arbitrary initial axes.
Using the spherical surface of the widget between the rings, or dragging on the screen is OK, but inevitably introduces slight rotations in axes that i don't want rotated.