so I added the icon here


CommandColumnEdit = new GridCommand() { Visible = true, Command=”customEditCommand”, Icon = “smart-icon-arrow-left”,  Label=”Verlauf”, },


and in the css of my project


.smart-grid-icon.smart-icon-arrow-left::before {
content: var(-smart-icon-arrow-left);


and I also tried


.smart-grid-icon.smart-icon-arrow-left::before {
content: var(–smart-icon-arrow-left);


but the icon is still not showing


the class seems to be applied to the div

<div><span title=”Verlauf” class=”smart-grid-icon smart-icon-arrow-left”></span></div>