Hi, I have found this issue a couple of times so I found this rather annoying. My current solution is I had to (gulp!) edit the core files directly, I wonder if there is another way to override some classes that just doesn't work with Ext.override.

I found that both Ext.chart.Highlight and Ext.core.Element cannot be overridden.

Example:
Code:
	// Stop charts from animating on mouse over.
	Ext.override(Ext.chart.Highlight, {
		highlightItem: function(item) {
			console.log('this isn't get called');
    },
	});