I've submitted QC report 45527 about a small, probably infrequently encountered issue with
TCheckListBox: when themes are not used and you're using the
Flatstyle, horizontal scrolling sometimes causes the checkboxes not to be redrawn properly.
Attached to the report are more details, screenshots and a sample project.
The problem somehow seems to be related to setting the clipping region in
TCheckListBox.DrawCheckmethod. I was unable, so far, to find out the exact cause of the problem.
My proposed workaround which prepares an in-memory bitmap of the checkboxes and uses no clipping on the control's canvas directly is also attached to the report.