Question

How can I increase the width of the jqgrid multiselect checkbox?

Answer 1

Have you checked this link Checkbox size in HTML/CSS. According to this there is no way to set size of checkbox in all browsers.

But you may able to change width of checkboxes in webkit browsers hardcoded like this :

 // Put this in jqGrid init to modify checkbox cell width
 gridComplete: function() {

    $("#yourid_cb").css("width","50px");
    $("#yourid tbody tr").children().first("td").css("width","50px");
 }

// override checkbox css 
   #yourid input[type="checkbox"] {    
     -webkit-transform: scale(2.0, 2.0)   
}

Demo : http://jsfiddle.net/gurkavcu/M8hnA