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