In Chrome, you can type into the Editor's fontName tool to select a font. In IE, however, you can't type in a font, but rather can only select one using the dropdown. It would be good to be able to give the user a consistent experience across browsers. Ideally that would mean allowing them to type in a font in IE, but if that is not possible it would be good to be able to configure/turn off the ability to type in the control in Chrome and other browsers.
Actually you can type in the fontName textbox in IE as well, however it'll behave as when typing in a regular dropdown list rather than a combobox. This can be classified as browser behavior, since the rendering and the dropdown component in each browser is the same.