Bug 127629 [Markers] problems view: keep selection stable
I20050214-0010 1. Select a grouping (e.g. Java problem type) and select a marker inside 2. Switch to another grouping Selection is gone. Same when - changing filter - a build adds new marker (in a different file)
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerView.java
};
	private class ContextProvider implements IContextProvider {
		public int getContextChangeMask() {
			return SELECTION;
		}
		public IContext getContext(Object target) {
			String contextId = null;