WPSClient : cannot select a polygon cluster as input geometry

[jjrom]

In the WPSClient, the 'Select on map' icon allows user to select a feature on map (point, line or polygon) as the input geometry for the process.
If a polygon cluster is selected instead of a simple feature, the selection is not done but instead the normal polygon cluster selection process occurs (i.e. opening the side panel with individual feature list)