Bug 51653 [navigation] Quick Outline: Should also show interface members
I200402102000 We should consider showing the inherited members for interfaces at least when the target type is an interface itself.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/JavaOutlineInformationControl.java
private OutlineLabelProvider() {
			super(AppearanceAwareLabelProvider.DEFAULT_TEXTFLAGS |  JavaElementLabels.F_APP_TYPE_SIGNATURE, AppearanceAwareLabelProvider.DEFAULT_IMAGEFLAGS);
		}
		
		/**
		 * {@inheritDoc}
		 */
		public Color getForeground(Object element) {
			if (fOutlineContentProvider.isShowingInheritedMembers()) {
				if (element instanceof IJavaElement) {
					IJavaElement je= (IJavaElement)element;
					if (fInput.getElementType() == IJavaElement.CLASS_FILE)
						je= je.getAncestor(IJavaElement.CLASS_FILE);
					else
						je= je.getAncestor(IJavaElement.COMPILATION_UNIT);
					if (fInput.equals(je)) {
						return null;
					}
				}
				return fForegroundColor;
			}
			return null;
		}
	}
	private class OutlineTreeViewer extends TreeViewer {