Preference page's configuration selection is not directly displayed

[WaldoFR]

When changing configuration selection to Custom, RNC class A, B, C or D, the user must Apply the configuration to have it being displayed in the two TableViewer of Metric & Rules.

This process isn't convenient for the user especially when setting when the preferences are already set on one of the RNC class and that the user choose "Custom" one as the Table stays not editable.