Don't destroy selection when getting focus

bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/history/GenericHistoryView.java

diff --git a/bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/history/GenericHistoryView.java b/bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/history/GenericHistoryView.java
index 1a21095..29be308 100644
--- a/bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/history/GenericHistoryView.java
+++ b/bundles/org.eclipse.team.ui/src/org/eclipse/team/internal/ui/history/GenericHistoryView.java
@@ -458,7 +458,7 @@
 	}
 
 	public void setFocus() {
-		if (isLinkingEnabled()) {
+		if (isLinkingEnabled() && lastSelectedElement != null) {
 			showLastSelectedElement();
 		}
 		getCurrentPage().setFocus();
@@ -505,6 +505,7 @@
 	}
 
 	public IHistoryPage showHistoryPageFor(Object object, boolean refresh, boolean force, IHistoryPageSource pageSource) {
+		lastSelectedElement= null;
 		if (Policy.DEBUG_HISTORY) {
 			String time = new SimpleDateFormat("m:ss.SSS").format(new Date(System.currentTimeMillis())); //$NON-NLS-1$
 			System.out.println(time + ": GenericHistoryView#showHistoryPageFor, the object to show is: " + object); //$NON-NLS-1$