private void updateAllocationOffsetLabel() {
		if (composite instanceof Structure) {
			int allocOffset = placementComponent.getAllocationOffset();
			String allocOffsetStr;
			if (placementComponent.isShowOffsetsInHex()) {
				allocOffsetStr = "0x" + Integer.toHexString(allocOffset);
			}
			else {
				allocOffsetStr = Integer.toString(allocOffset);
			}
			String text = "Structure Offset of Allocation Unit: " + allocOffsetStr;
			allocationOffsetLabel.setText(text);

			int offset = placementComponent.getAllocationOffset();
			decrementButton.setEnabled(offset > 0);
			int length = composite.isZeroLength() ? 0 : composite.getLength();
			incrementButton.setEnabled(offset < length);
		}
	}
<code>BitFieldEditorPanel</code> provides the ability to add or modify bitfields
within non-packed structures.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/BitFieldEditorPanel.java