Rows or columns.
OptionaldisabledWhether a press would be refused (the sheet is protected); the button shows it.
The level the button shows, from 1.
Shows the groups above this level and collapses the rest.
Whether the headers this level reveals are showing somewhere: its button, and every one below
it, would show nothing new. The default renderer does not mark these; it sets data-shown.
The edge of the square the button fills, in pixels.
A localized description of what a press does.
Props for one of the level buttons
1..n.