TableGroupMenu
TableGroupMenu is the toolbar that takes the place of the table header while rows are selected, with a select-all checkbox and the actions that apply to the selection.
The Table README describes it in full.

Props
Stories
Default
The toolbar a user sees after selecting rows, with the actions that apply to them; change any other prop live in the Controls panel below.

Checked
Every row is selected, so the checkbox is ticked and a click on it clears the selection (isChecked).

Indeterminate
Some rows but not all are selected, so the checkbox is partly ticked and a click on it selects the rest (isIndeterminate).

With Header Label
A text in place of the checkbox, for a toolbar that acts on something other than a list of rows the user can select all of (headerLabel).

Closeable
A cross before the info panel button, for a toolbar the user can dismiss without clearing the selection by hand (isCloseable, onCloseClick).

Blocked
Every action greyed out and ignoring clicks while an operation on the selection is still running (isBlocked); the checkbox stays usable.

Info Panel Open
While the info panel is open, its button at the end is drawn in the accent colour on a round background, so the user sees that a click closes the panel (isInfoPanelVisible).

Right To Left
In a right-to-left interface the checkbox moves to the right edge, the actions follow it leftwards and the info panel button sits at the left edge with its icon mirrored.

Css Customization
The variable set on a wrapper -- it is listed under CSS variables in the Table README.