The included controls have a very light appearance. The feature might be not supported by all themes.
sap.ui.commons.ToolbarDesign.Standard
The toolbar elements such as buttons for example have their normal visual design, and the toolbar appears solid. The feature might be not supported by all themes.
sap.ui.commons.ToolbarDesign.Transparent
The controls included in the toolbar have a normal visual design where the toolbar appears transparent. The feature might be not supported by all themes.