Creating a background for GroupElement

[TorbjørnDalløkken2]

Hi.

I'm working on an add-in which creates several layout-elements, including a groupelement which contains some text and a scalebar. I'm able to add background / outline for each of the elements in the group, but not on the group itself.  How do I do this? I can't see any methods or properties on the GroupElement-object, nor the CIM-definition. 

Here's how I've created the GroupElement.

ElementInfo info = new ElementInfo();
  info.CornerRounding = 25;

GroupElement groupElement = ElementFactory.Instance.CreateGroupElement(
  elementContainer: Module1.layout,
  elements: elementList,
  elementName: "JSRMålestokkGruppe",
  groupElementInfo: info
);

Can anyone help me with this and point me in the right direction?

[Wolf · Accepted solution]

You might have already done this, but there is a utility called CIM Viewer that you can download from GitHub and builder:   GitHub - Esri/arcgis-pro-sdk-cim-viewer

using the CIM Viewer you can then examine the CIMGroupElement in order to come up with a programmatic approach:

Using the objects that i discovered using the CIMViewer i build the following code snippet that gets the CIM Group's graphic frame and changes the width and the color of the group's frame (name MyGroup).  

internal class ChangeGroupElement : Button
{
  private static CIMColor Red = new CIMRGBColor
  {
    R = 255,
    G = 0,
    B = 0,
    Alpha = 100// 0 for transparent and 100 for opaque
  };
  private static CIMColor Black = new CIMRGBColor
  {
    R = 0,
    G = 0,
    B = 0,
    Alpha = 100// 0 for transparent and 100 for opaque
  };
  protected override async void OnClick()
  {
    // Find 'MyGroup' and make changes
    var layout = LayoutView.Active?.Layout;
    if (layout == null)
    {
      MessageBox.Show("No active layout view");
      return;
    }
    var grp = layout.FindElement("MyGroup");
    if (grp == null)
    {
      MessageBox.Show("MyGroup not found");
      return;
    }
    try
    {
      await QueuedTask.Run(() =>
      {
        var cimGrp = grp.GetDefinition() as CIMGroupElement;
        if (cimGrp != null)
        {
          // check the graphic frame (see CIMViewer)
          if (cimGrp.GraphicFrame != null)
          {
            // get the border symbol in the graphic frame
            var borderSym = cimGrp.GraphicFrame.BorderSymbol as CIMSymbolReference;
            if (borderSym != null && borderSym.Symbol != null)
            {
              // the border symbol is comprised of SymbolLayers
              // ... change the first SymbolLayer which is a CIMSolidStroke
              var symbol = borderSym.Symbol as CIMLineSymbol;
              if (symbol.SymbolLayers != null)
              {
                var solidStroke = symbol.SymbolLayers.OfType<CIMSolidStroke>().FirstOrDefault();
                if (solidStroke != null)
                {
                  var width = solidStroke.Width + 1;
                  solidStroke.Color = width % 2 == 0 ? Red : Black;
                  solidStroke.Width = width;
                }
              }
            }
          }
          grp.SetDefinition(cimGrp);
        }
      });
    }
    catch (Exception ex)
    {
      MessageBox.Show(ex.ToString());
    }
  }
}