How to style selection dashed rectangle in diagram? It's really difficult to see as it have small thickness.
If you are using 14.2 or later you can access the selection rectangle by going to your Infragistics installation directory and grabbing the default style for the XamDiagram. This is the location: C:\Program Files (x86)\Infragistics\2014.2\WPF\DefaultStyles\XamDiagram\generic.xaml. Once you have the default style you can search for "SelectionRectangle". This is the dashed rectangle that you want to adjust.