Steps to Reproduce

1. run the attache file
2. click the button "prepend 1st column dynamically"

Current Result

2 columns have checkmarks

Expected Result

just 1st column has checkmark

Debug Information

1. suggest to change listbox implementation: render checkmarks in a separate internal column instead of inside the 1st column. Current implementation has a problem: if hiding the 1st column, the checkmark is hidden, too.

Workaround

1. create an empty 1st column to avoid this
2. call invalidate()