I have not found any reference to such a boolean field in the description. Background: the data has several columns with 0/1-yes/no-true/false values. Ideally the positive values should be represented in the grid with a symbol like a bullet or a checked box or a cross and the negative values should stay empty.
As an example you can check this image:
http://www.conceptdraw.com/samples/resource/images/solutions/finance-&-accounting-charts/MARKETING-AND-SALE-DIAGRAMS-Matrices-Feature-Comparison-Matrix-Chart-Template.png
Does something like that exists?
You can refer demos/misc/example-all.php
Following code config is required for our case.
$col = array();
$col["title"] = "Closed";
$col["name"] = "closed";
$col["width"] = "50";
$col["editable"] = true;
$col["edittype"] = "checkbox"; // render as checkbox
$col["editoptions"] = array("value"=>"1:0"); // with these values "checked_value:unchecked_value"
$col["formatter"] = "checkbox";
$cols[] = $col;