private boolean isFromPreferredDtm(DataType dt) {
		if (dt == null) {
			return false;
		}

		if (preferredDtm != null) {
			DataTypeManager altDtm = preferredDtm instanceof CompositeViewerDataTypeManager compDtm
					? compDtm.getOriginalDataTypeManager()
					: null;
			DataTypeManager dtDtm = dt.getDataTypeManager();
			return dtDtm == preferredDtm || dtDtm == altDtm;
		}
		return false;
	}
Remove any unwanted data type items, like arrays.
Ghidra/Features/Base/src/main/java/ghidra/app/util/datatype/DataTypeDropDownSelectionDataModel.java