Thingworx 8.3.3 :
Below picture shows implementation using repeater widget.
Thingworx 8.5.2 :
I want to implement the same using collection widget in 8.5.2 version but inner mashups are not stretching horizontally.I tried both Table/flow views.
We suspect this may be a mashup layout issue. Please provide a screenshot of the inner mashup layout in 8.5.2 and a screenshot of everything at runtime using the collection widget.
According to your UI, you have to use Flow. What is not stretching horizontally? Are you getting horizontal scrollbar or what? Also check Flow layout alignment and gravity in properties.