Gecko and Trident are missing SVGElement.prototype.focus and SVGElement.prototype.blur which means you cannot focus SVG elements by script. In Trident you can work around this issue by making SVGElement use HTMLElement.prototype.focus. Gecko does not tolerate this hack and throws an error: TypeError: 'focus' called on an object that does not implement interface HTMLElement.

Focusing SVG elements works fine in Blink and WebKit because they expose focus at Element.prototype.focus, which is inherited by HTMLElement and SVGElement.