Allow to add Vizlib line object in KPI designer

Vizlib KPI designer allows to add master visualizations. Most of the Qlik and Vizlib visualizations can be added, but it is not possible to include the Vizlib line object. It would be of great help if I could add this type of master visualization to the KPI designer.

Use case: I'm trying to implement a complex legend using the KPI designer. Besides various shapes and texts it should contain the line object with a color gradient (see attachment) and measures for minimum/maximum at the bottom/top of the scale.