jQuery - SlickGrid - sometime my customer gets this message

[szlamany]

The attached screen shot shows an error message that sometimes appear for one of my customers. If they immediately try again to open this "grid" it works - so it's a sporadic problem.

And I've never gotten it myself - nor have dozens of others users...

I searched in the slick.grid.js source and found this code

            if ($style[0].styleSheet) { // IE
                $style[0].styleSheet.cssText = rules.join("");
            }
            else {
                $style[0].appendChild(document.createTextNode(rules.join(" ")));
            }

            var sheets = document.styleSheets;
            for (var i = 0; i < sheets.length; i++) {
                if ((sheets[i].ownerNode || sheets[i].owningElement) == $style[0]) {
                    stylesheet = sheets[i];
                    break;
                }
            }

Which I am not in control of...

And they are using Firefox