Hi Alex,

I'm afraid that the grid doesn't offer a "show all/hide all" functionality out of the box.
I'd also like to make notice of the design decision which we took when we implemented the igGrid:
The grid must display at least one column. 
(and when you think about it, if there are no columns to show, why display an entire grid at all?)

With this in mind, you can apply all kinds of code tricks in order to "hide" or show all columns.
For example you can hide the entire grid when there are no columns to display using either of these approaches:

//If you want to collapse the space that would otherwise be taken by the lack of a grid
$("#Grid1").hide();
//If you want to keep the space on the page that would be taken by the lack of a grid
$("#Grid1").css('visibility','hidden');

Also, here's a sample "show all columns" function:

function showAllColumns()
{
    //Just in case the the grid was hidden before
    if($("#Grid1").css('visibility') === "hidden")
    {
        $("#Grid1").css('visibility','visible');
    }
    else 
    {
        $("#Grid1").show();
    }
    
    var gridColumns = $("#Grid1").igGrid("option", "columns");
    
    for(var i = 0; i < gridColumns.length; i++)
    {
        if(gridColumns[i].hidden)
        {
            $("#Grid1").igGrid("showColumn", gridColumns[i].key);
        }
    }
}

I'm also attaching a working HTML sample page where you can see my suggestions in effect.

Hope this helps,
Borislav 

1. Hook up to the igGridHiding feature's columnHidden event. Keep in mind that it' only fired when a column is hidden through the UI, not the API! 
2. Keep a dictionary/hashtable of the states of the columns each time the event is fired. Each entry in that dictionary can be a dictionary with column keys being the keys and the hidden flags - the values. You can get the column keys and the hidden flags from the igGrid's columns collection ($("#Grid1").igGrid("option","columns"))
3. Make the user save entries from that dictionary as desired states.
4. Simply call the igGrid or igGridHiding (whichever you prefer)'s showColumn() and hideColumn() API methods to display the columns in the desired configuration.

How does sound to you? Good enough or not? :)

Cheers,
Borislav