If you are hovering over a node preview and open the context menu, then click back into the node preview, the preview collapse button won't be displayed correctly and won't work when clicked. You have to move the pointer away from the node and back again to get the button to appear and work correctly.

1. Install Unity
2. Open the attached project
3. Open PBRGraph.shadergraph
4. Hover over the preview window of the Gradient Noise Node
5. Right click to bring up the context menu
6. Left click into the preview window of the Gradient Noise Node

Expected Result:
The context menu should close and the preview collapse button should appear and function as normal.

Actual Result:
The context menu closes but the preview collapse button does not appear. If you hover over where the button should appear then part of it does, but it's not functional.

Tested on Windows.

Occurs on:
2019.1.0a9 with Shader Graph 5.0.0-preview

Does not occur on:
2018.3.0b11 with Shader Graph 4.1.0-preview