Bug 420950 - Force cornerRadius to 0 if less than 6.  Prevents NPE.

Change-Id: I41997b6e3c6441870a9901c10ca0adf4a9b08468
Signed-off-by: Mike Marchand <mmarchand@cranksoftware.com>
diff --git a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/CTabRendering.java b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/CTabRendering.java
index c30c85b..e4652f1 100644
--- a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/CTabRendering.java
+++ b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/CTabRendering.java
@@ -922,7 +922,7 @@
 
 	@Override
 	public void setCornerRadius(int radius) {
-		cornerSize = radius;
+		cornerSize = (radius < 6) ? 0 : radius;
 		parent.redraw();
 	}