fires when undo/redo operations are performed
| action |
webix.ui({
view:"spreadsheet",
toolbar:"full",
data:spreadsheet_data,
on:{
onUndo(action, row, column, value, dir, extra){
if(action == "paste"){
//do smth
} else if(action == "grid-change"){ //add or remove row/col
//do smth
}
},
}
});