Bug 42346 [Tasks] Associated task not remaining with associated line
I was following the instructions in the Workbench User Guide...Basic Tutorial/Associated tasks. After creating the task, I inserted lines above it. The task's location column didn't change to reflect the task's new position, so I saved the file, but it still didn't update. Per the tutorial's instructions, I chose "Mark Completed" in the task's context menu and the task moved to a different line. I chose "Delete Completed Tasks" from the context menu and got an info box that said "No user-editable completed tasks to delete". The only way I found to remove the task was to choose "Remove task" from the context menu I got when I right-clicked on the task marker in the marker bar.
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/markers/internal/Util.java
for (int i = 0; i < n; ++i) {
			if (i != 0)
				sb.append('/');
			sb.append(path.segment(i));
		}
		return sb.toString();
	}
	
	public static String getResourceName(IMarker marker) {
		return marker.getResource().getName();
	}
	
	public static boolean isEditable(IMarker marker) {
		if (marker == null) {
			return false;
		}
		try {
			return marker.isSubtypeOf(IMarker.BOOKMARK) || 
				   (marker.isSubtypeOf(IMarker.TASK) && 
				   marker.getAttribute(IMarker.USER_EDITABLE, false));
		}
		catch (CoreException e) {
			return false;
		}
	}
	private Util() {
		super();
	}
}