private void setOperandAttributes(int opIndex, String operandText) {

		operandLabels[opIndex].setText(operandText);
		operandLabels[opIndex].setForeground(getOperandColor(opIndex));

		if (activeIndex == opIndex) {
			operandLabels[opIndex].setBorder(ETCHED_BORDER);
			operandLabels[opIndex].setBackground(EditReferencesProvider.BG_COLOR_ACTIVE_OPERAND);
			operandLabels[opIndex].setOpaque(true);
		}
		else {
			operandLabels[opIndex].setBackground(getParent().getBackground());
			operandLabels[opIndex].setBorder(EMPTY_BORDER);
			operandLabels[opIndex].setOpaque(false);
		}
	}
Set the operand text and attributes
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/references/InstructionPanel.java