ID 420675 - The red border when using the Ripple Edit tool on Roto/RotoPaint only draws the bottom side

Problem summary
The red border when using the Ripple Edit tool on Roto/RotoPaint only draws the bottom side

Customer reported version
nuke.12.0v3

Customer reported platform
centos7

Steps to reproduce

1) Open Nuke

2) Create a Roto/Rotopaint node 

3)  Activate the Select All tool

in the RotoPaint toolbar

4) Click the ripple edit

button in the RotoPaint tool settings

Expected behaviour

To see the red border around the Viewer

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Actual behaviour
The red border only appears on the bottom of the Viewer

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Reproduced by support
This bug has been reproduced in:

Nuke 12.0v3 - Windows 10 - CentOS 7.7

Nuke 12.0v1 - Windows 10 - CentOS 7.7 - regression

Unable to reproduce bug in:

Nuke 12.0v3 - MacOSX 10.13
Nuke 11.3v6 - Windows 10 - CentOS 7.7

Earliest version tested
Nuke 11.3v6 - This issue doesn't appear in this version and has regressed