Hello Luke,

Thank you for your feedback.

I have upvoted this Feature Request on your behalf. As we actively monitor the community interest in requested features to determine which to implement in the future.

Currently we have a Knowledge Base article that showcases how to create an external columns menu with checkbox functionality outside to the Kendo UI Grid. As workaround I suggest the following approach that is based on the article above and utilizes the Grid's showColumn and hideColumn methods.

1. Add a div container with id="columnChooser"
2. Make sure the Grid is initialized and get its data.
3. Get the Grid's columns and the number of columns in 2 global variables
4. Iterate over the columns and for each column append a checkbox input to the columnChooser container
5. Subscribe to the input event of the checkboxes
6. In the handler if the checkbox is checked show the Grid's column and increase the numOfColumns counter
7. If the checkbox is unchecked, make sure the numOfColumns  counter is bigger than 1 (not to remove all the columns) 
8. Only if the number of columns is bigger than 1, remove the column and decrease the numOfColumns

   $(document).ready(function () {
           var grid = $("#grid").data("kendoGrid");
   
           var columnValues = grid.columns;
           var numOfColumns = grid.columns.length; 
   
           columnValues.forEach(column => {
               $("#columnChooser").append(`<span class='${column.field} p-2'></span>`)
               $(`.${column.field}`).append(`<label for="${column.field}">${column.title}</label>`)
               $(`.${column.field}`).append(`<input id="${column.field}" type="checkbox" checked=true>`)
   
               $(`#${column.field}`).on("input", function (e) {                
                       if ($(`#${e.currentTarget.id}`).prop("checked")) {
                           grid.showColumn(e.currentTarget.id)
                           numOfColumns++;
                       } else {
                           if (numOfColumns > 1) {
                               numOfColumns--;
                               grid.hideColumn(e.currentTarget.id)
                           } else {
                               $(`#${e.currentTarget.id}`).prop("checked", true)
                       }
                   }
               })
           })
       })

I hope the above is helpful in the current scenario. Please don't hesitate to contact me, should additional questions occur.

Regards,
Stoyan
Progress Telerik