How to reproduce:
1. Create a new LWRP project
2. Install Shadergraph through the package manager
3. Create a new Shadergraph and open it
4. Create an Ellipse node
5. Double-click/drag the X value
6. Click on the node again and hover over the values

Expected result: Values only change when click-dragged or entered directly
Actual result: A simple mouse hover changes the value, clicking other nodes or typing in a new value and pressing enter does not fix the mouse hover issue

Reproduced in: 2018.2.0b6, 2018.2.0a3
Couldn't test: 2018.2.0a2, 2018.2.0a1

Note: Reproduces on both HDRP and LWRP, tested with Shadergraph version - 1.1.9

Verified in: 2018.3.0a6 (Shadergraph version - 3.0.0)