Where is the opacity setting on the SimpleFillSymbol?

[LukePatterson]

I need to set the fill color opacity for the simple fill symbol (in the WPF SDK there was an Opacity property for the SimpleFillSymbol). I tried the layer opacity but it also impacts the outlines for my symbol. How can I achieve this?

[DominiqueBroux · Accepted solution]

You can set the FillSymbol Color to a color having an alpha component. So the FillSymbol outline won't be impacted.