Checkedlistbox Multicolumn

Although CheckedListBox has MultiColumn property and you can set it to true, but it only arranges list of items in multiple columns flowing items top to down then right, based on height of control

■ 1         ■ 5
■ 2         ■ 6
■ 3         ■ 7
■ 4

So if you really need multiple column, consider using DatGridView or ListView that are real multi column controls.

Setting the MultiColumn property to true doesn't allow you to add more columns manually. It just 'wraps' items to the next column instead of showing a vertical scrollbar once the items exceed the height of the CheckedListBox.

If you want a two column control, either use a grid control of some kind or a ListView control. By setting a ListView control's View property to View.Details, you can use it as a multicolumn 'grid'.