using Laz 3.4 or maybe earlier who knows.
Drop a TCoolbar on the form, add one band.
don't put any controls on it, just leave it empty.
Drag mode set to manual! < important here.
place mouse over band, left click and drag starting over band and then outside on to form.
crash!
it ends up entering the StartDrag code with an NIL control
basically, being in manual mode it's not supposed to start the operation, but it does while over Band on a Tcoolbar.
Please give it a try yourself.
Maybe this does not happen with controls on it, but the band always has some free area for you to grab onto.