Question: Is there a way to disable multi select?

Answer: 
I know this is an old question, but updates to Slickgrid now allow you to disable multiSelect in the grid options:

```
var options = {
            editable: false,
            enableCellNavigation: true,
            asyncEditorLoading: false,
            multiSelect: false
        };

```

With this option, clicking while holding a ctrl or shift does nothing, and undesirably, you cannot deselect a cell with ctrl + click, or clicking the selected cell again
Regarding your question, disable to multiple select is quite simple? Isn't it?

```
<select multiple="multiple" disabled = "true">
    <option value="1"> One
    <option value="2"> Two
    <option value="3"> Three        
</select>

```