As the suggested functionality in comment 3 is likely to be left for implementation with the notebookbar, the single toolbar mode UNO command should be a toggle/checkbox command that when toggled on enables (i.e. Visible=true)
View > Toolbars > Standard (Single Mode)
and disables (i.e. Visible=false)
View > Toolbars > Standard View > Toolbars > Formatting View > Toolbars > Image View > Toolbars > Drawing Object Properties View > Toolbars > Frame (Writer) View > Toolbars > Table (Writer) View > Toolbars > Bullets and Numbering (Writer) View > Toolbars > Text Object (Writer) View > Toolbars > Text Formatting (Calc)
When the single toolbar mode UNO command is toggle off, it does the reverse.
As the suggested functionality in comment 3 is likely to be left for implementation with the notebookbar, the single toolbar mode UNO command should be a toggle/checkbox command that when toggled on enables (i.e. Visible=true)
View > Toolbars > Standard (Single Mode)
and disables (i.e. Visible=false)
View > Toolbars > Standard
View > Toolbars > Formatting
View > Toolbars > Image
View > Toolbars > Drawing Object Properties
View > Toolbars > Frame (Writer)
View > Toolbars > Table (Writer)
View > Toolbars > Bullets and Numbering (Writer)
View > Toolbars > Text Object (Writer)
View > Toolbars > Text Formatting (Calc)
When the single toolbar mode UNO command is toggle off, it does the reverse.