window.onload = function () {
  var designer = new GC.Spread.Sheets.Designer.Designer(document.getElementById("gc-designer-container"));
  var spread = designer.getWorkbook();
  var sheet = spread.getSheet(0);

  var config = GC.Spread.Sheets.Designer.DefaultConfig;
  config.contextMenu.push("myItem");

  config.commandMap = {
    myItem: {
      text: "my-item",
      commandName: "myItem",
      subCommands: ['subCmd1', 'subCmd2', 'subCmd3']
    },
    subCmd1: {
      commandName: "subCmd1",
      name: "subCmd1",
      text: "1st First",
      subCommands: ['sub_subCmd1'],
      execute: function () {
        alert("SubCmd1")
      }
    },
    subCmd2: {
      commandName: "subCmd2",
      name: "subCmd2",
      text: "2st Second",
      execute: function () {
        alert("subCmd2")
      }
    },
    subCmd3: {
      commandName: "subCmd3",
      name: "subCmd3",
      text: "3st Thrid",
      execute: function () {
        alert("subCmd3")
      }
    }
  }
}