The validation results marker bar appears at the right side of a diagram pane, if the diagram contains symbols of invalid elements.
The markers are shown even for the items that are not currently visible on the screen (you may need to scroll down to see them). The marker bar shrinks to fit the screen and displays relative positions of annotated symbols on the axis of ordinates. Every marker is colored according to the violation severity.
Clicking a marker on the bar selects the appropriate symbol on the diagram pane. Moving the mouse over the marker eye (the red square at the top-right corner of the diagram pane) opens the summary of the diagram validation results.