ID 138056 - Rotopaint - crash with smear tool and "pressure alter size"

Problem summary
Nuke crashes when pressure sensitivity is enabled on the smear brush on the rotopaint node and you are using a pressure based input, like a wacom tablet

Steps to reproduce

1) Open Nuke when using a tablet

2) Add a Checkerboard

3) Add a Rotopaint node and select the smear brush, and enable the toolbar_dynamic_size knob

4) Paint a couple of strokes and until it crashes.

Reproduced by support

This problem has been reproduced on:

Nuke 10.5v3 - MacOSX 10.12 

Nuke 10.5v1 - MacOSX 10.12 

Nuke 10.0v6 - MacOSX 10.12 - CentOS 6.8 - Windows 10

Nuke 10.0v1 - MacOSX 10.12

Nuke 9.0v9 - MacOSX 10.12

Nuke 9.0v1 - MacOSX 10.12

Nuke 8.0v7 - MacOSX 10.12 - Windows 10

Expected behaviour
For the smear brush to adjust size with pressure while painting 

Actual behaviour
Nuke crashes