The problem seems to be with datasets that have a simple style sheet associated with them. For example, adding either buildings or bridges to a scenario and then clicking on the collapse/expand triangle in the scenario tree viewer throws a Number format exception:

java.lang.NumberFormatException: For input string: "av"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at edu.illinois.ncsa.ergo.gis.ui.util.UIUtils.hexToRgb(UIUtils.java:143)
at edu.illinois.ncsa.ergo.gis.ui.util.UIUtils.getColorForHex(UIUtils.java:83)
at edu.illinois.ncsa.ergo.gis.ui.util.StyleUtils.generateSymbolImage(StyleUtils.java:142)
at edu.illinois.ncsa.ergo.gis.ui.types.Legend.getLegendEntries(Legend.java:149)
at edu.illinois.ncsa.ergo.eq.ui.providers.ErgoEQScenarioManagerContentProvider.getChildren(ErgoEQScenarioManagerContentProvider.java:125)
at org.eclipse.jface.viewers.AbstractTreeViewer.getRawChildren(AbstractTreeViewer.java:1372)
at org.eclipse.jface.viewers.TreeViewer.getRawChildren(TreeViewer.java:353)
at org.eclipse.jface.viewers.StructuredViewer.getFilteredChildren(StructuredViewer.java:905)
at org.eclipse.jface.viewers.AbstractTreeViewer.getSortedChildren(AbstractTreeViewer.java:617)
at org.eclipse.jface.viewers.AbstractTreeViewer$1.run(AbstractTreeViewer.java:815)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:791)
at org.eclipse.jface.viewers.TreeViewer.createChildren(TreeViewer.java:611)
at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:762)
at org.eclipse.jface.viewers.AbstractTreeViewer.handleTreeExpand(AbstractTreeViewer.java:1495)
at org.eclipse.jface.viewers.TreeViewer.handleTreeExpand(TreeViewer.java:903)
at org.eclipse.jface.viewers.AbstractTreeViewer$4.treeExpanded(AbstractTreeViewer.java:1507)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:132)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4454)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1388)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1412)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1397)
at org.eclipse.swt.widgets.Tree.gtk_test_expand_row(Tree.java:2084)
at org.eclipse.swt.widgets.Widget.windowProc(Widget.java:2130)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4674)
at org.eclipse.swt.internal.gtk.OS._gtk_main_do_event(Native Method)
at org.eclipse.swt.internal.gtk.OS.gtk_main_do_event(OS.java:9106)
at org.eclipse.swt.widgets.Display.eventProc(Display.java:1253)
at org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native Method)
at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java:2477)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3407)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
at edu.illinois.ncsa.ergo.eq.rcp.Application.start(Application.java:39)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:380)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
at org.eclipse.equinox.launcher.Main.main(Main.java:1438)