Function
Returns the button on the pointer device represented by the specified index.
button-index-name index => button
<integer>.
one-of(#"left", #"middle", #"right").
duim-sheets
duim-sheets
Returns the button on the pointer device connected to the computer (typically a mouse) represented by index. The index is either 0, 1, or 2, these values corresponding to the left, middle, or right buttons, respectively.