public void setBaseFont(Font font) {
		baseFont = font;
		baseMetrics = getFontMetrics(font);
		metricsMap.clear();
	}
callback for when the selected display field changes.

@param index the index in the JList of the selected field.
Ghidra/Features/Base/src/main/java/ghidra/app/util/viewer/options/OptionsGui.java