 the current time, there is no support for separator lines
(<a href="RowColumnDefinition.html#separatorStroke" class="tsd-kind-accessor">go.RowColumnDefinition.separatorStroke</a>, <a href="RowColumnDefinition.html#separatorStrokeWidth" class="tsd-kind-accessor">go.RowColumnDefinition.separatorStrokeWidth</a>,
and <a href="RowColumnDefinition.html#separatorDashArray" class="tsd-kind-accessor">go.RowColumnDefinition.separatorDashArray</a> properties)
nor background (<a href="RowColumnDefinition.html#backgrou