Is it possible to have dropdown menu type list from icon, as it is available in Groupedbar Full, in normal / default Toolbar layout?
(edit: activated screenshot -AK)
From the LibreOffice.org help pages:
To add a button to the list of Visible Buttons:
Choose Tools - Customize, and click on the Toolbars tab.
In the Toolbars box, select the toolbar you want to change.
Click Add Commands , select the new command, then click Add.
If you want, you can rearrange the Commands list by selecting a command name and clicking Move Up and Move Down.
Click OK.