Two rendering issues with UGUI

Hi there guys,

Recently I faced two UGUI related issues which is really hard to resolve.
Hope someone have idea to handle this situation.

I'm using 5.4.0p2 the latest unity build at the moment.

1. world space UGUI on Rendertexture is always in front of other renderers.
- this is easily reproduced with GoogleVR sdk.
Place a box in front of a world canvas, And the canvas will be rendered first while it's distance is far from camera than the box.

2. Canvas rendering is slower than actual render timing.
- This lead a frame gap between canvas changes. for example if you make a VR recticle with world space canvas, this recticle will follow camera's position and rotation after 1 frame later.
This problem occurs both GoogleVR and Native GearVR.

If there's anyone who resolved these issues. please let me know about the solution.

Thank you in advance!

 

I have attached sample project to reproduce bugs.
Please some1 check this out!