Bug 318944 CSSSWTEngineImpl leaks memory
CSSSWTEngineImpl stores too many element contexts. In a memory snapshot, the HashMap size was 15559. This is most probably a leak.
bundles/org.eclipse.e4.ui.css.swt/src/org/eclipse/e4/ui/css/swt/engine/CSSSWTEngineImpl.java
super.registerCSSProperty("unselected-image-visible", CSSPropertyUnselectedImageVisibleSWTHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyUnselectedImageVisibleSWTHandler.class,
				CSSPropertyUnselectedImageVisibleSWTHandler.INSTANCE);
		
		super.registerCSSProperty("tab-height", CSSPropertyTabHeightHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyTabHeightHandler.class,
				CSSPropertyTabHeightHandler.INSTANCE);
		
		super.registerCSSProperty("show-close", CSSPropertyShowCloseHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyShowCloseHandler.class,
				CSSPropertyShowCloseHandler.INSTANCE);
		
		super.registerCSSProperty("alignment", CSSPropertyAlignmentSWTHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyAlignmentSWTHandler.class,
				CSSPropertyAlignmentSWTHandler.INSTANCE);
		
		
		super.registerCSSProperty("unselected-tabs-color", CSSPropertyUnselectedTabsSWTHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyUnselectedTabsSWTHandler.class,
				CSSPropertyUnselectedTabsSWTHandler.INSTANCE);
		
		
		super.registerCSSProperty("tab-renderer", CSSPropertyTabRendererSWTHandler.class);  
		super.registerCSSPropertyHandler(CSSPropertyTabRendererSWTHandler.class,
				CSSPropertyTabRendererSWTHandler.INSTANCE);