@Override
	public DataType promptForDataType(String filterText) {
		DataTypeChooserDialog dialog = new DataTypeChooserDialog(this);
		if (!StringUtils.isBlank(filterText)) {
			dialog.showPrepopulatedDialog(tool, filterText);
		}
		else {
			tool.showDialog(dialog);
		}

		return dialog.getSelectedDataType();
	}
Create the actions for the menu on the tool.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/DataTypeManagerPlugin.java