In the View tab of the Options... dialog, check Enable function code hotspots.
Check this option to enable the link from the function code hotspot [FCN] (or AI/DI import block) to the function code index. If Enable function code hotspots is checked, clicking on a function code hotspot in the content pane will cause the index of all the uses of that function code to be displayed in the index pane. If it is disabled, clicking on a function code number will have no result.