It's very easy to reproduce actually:
- New scene
- Created a NGUI 2D UI with NGUI -> Create -> 2D UI
- Created a widget under the UI Root with NGUI -> Create Widget
- Set Scaling Style of UIRoot to FixedSize and Manual Height to 1080
- Anchored Widget to UIRoot (Unified, OnUpdate, Left to Left, Right to Right, Top to Top, Bottom to Bottom, absolute offsets all 0)
- I have the scene and game view open. The game view is set to 1920x1080 resolution fix.
- If I now resize the game view (resolution still at 1920x1080), the local Y position of the widget transform changes as well as the height dimension of the UIWidget component.
I tried to debug the issue a bit and got till the NGUITools.GetSides (this Camera cam, float depth, Transform relativeTo) which gives different sides each time the game view is resized. Maybe this info helps with debugging