Some time ago. the fix for 0031900: Order of events: TEdit / TListBox broke a component of mine. I think that the fix does the right thing, however, I don't know how to work around it. My component is composed from an ancestor of TMyComboListbox and some other components.
In TMyComboListbox.MouseDown, I call ItemAtPos (Point (X, Y), TRUE). This used to work perfectly, but after 31900, WMKillFocus on another component gets called before mouse down. Unfortunately, on kill focus, I close the list box. I guess, I need to do the closing in reaction to some other event, but which one? I need that it gets closed on any click outside of my composed component.