Patch Set 2: I would prefer that you didn't submit this

Now I get an exception when I toggle the date format in the menu:

org.eclipse.swt.SWTException: Widget is disposed
	at org.eclipse.swt.SWT.error(SWT.java:4083)
	at org.eclipse.swt.SWT.error(SWT.java:3998)
	at org.eclipse.swt.SWT.error(SWT.java:3969)
	at org.eclipse.swt.widgets.Widget.error(Widget.java:468)
	at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:340)
	at org.eclipse.swt.widgets.Table.deselectAll(Table.java:1966)
	at org.eclipse.jface.viewers.TableViewer.doDeselectAll(TableViewer.java:277)
	at org.eclipse.jface.viewers.AbstractTableViewer.setSelectionToWidget(AbstractTableViewer.java:908)
	at org.eclipse.jface.viewers.StructuredViewer.setSelectionToWidget(StructuredViewer.java:1741)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1429)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1383)
	at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1485)
	at org.eclipse.jface.viewers.ColumnViewer.refresh(ColumnViewer.java:537)
	at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1444)
	at org.eclipse.egit.ui.internal.history.GitHistoryPage.setupFileViewer(GitHistoryPage.java:1536)
	at org.eclipse.egit.ui.internal.history.GitHistoryPage.initAndStartRevWalk(GitHistoryPage.java:1368)
	at org.eclipse.egit.ui.internal.history.GitHistoryPage$2.propertyChange(GitHistoryPage.java:609)
	at org.eclipse.ui.preferences.ScopedPreferenceStore$3.run(ScopedPreferenceStore.java:375)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.ui.preferences.ScopedPreferenceStore.firePropertyChangeEvent(ScopedPreferenceStore.java:372)
	at org.eclipse.ui.preferences.ScopedPreferenceStore.setValue(ScopedPreferenceStore.java:813)
	at org.eclipse.egit.ui.internal.history.GitHistoryPage$GitHistoryPageActions$BooleanPrefAction.run(GitHistoryPage.java:129)