boolean canMoveParameterDown() {
		if (selectedParams.size() != 1) {
			return false;
		}
		ParamInfo p = selectedParams.iterator().next();
		if (p.getOrdinal() < getAutoParamCount() || p.getOrdinal() >= (getParamCount() - 1)) {
			return false;
		}
		if (canUseCustomStorage() && functionData.hasParameters()) {
			List<ParamInfo> parameters = getParameters();
			if ("this".equals(parameters.get(0).getName())) {
				return false;
			}
		}
		return true;
	}
Get the effective function to which changes will be made.  This
will be the same as function unless it is a thunk in which case
the returned function will be the ultimate non-thunk function.
@return non-thunk function
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/editor/FunctionEditorModel.java