ToolbarItem.Tag
From Xojo Documentation
Property (As Variant )
aToolbarItem.Tag = newVariantValue
or
VariantValue = aToolbarItem.Tag
New in 2019r2
Supported for all project types and targets.
or
VariantValue = aToolbarItem.Tag
New in 2019r2
Supported for all project types and targets.
A “hidden” value associated with the toolbar item.
Notes
The tag is accessible via code when the user chooses the toolbar item but, unlike the Caption property, is not displayed in the toolbar.
Example
This example is in the Toolbar Initialized event of the main window.
Me.SaveButton.Tag = folderItemToSave