Minimum Height in QDockWidget widget

Hy everybody (and sorry for my bad english…), I got a mystical behaviour with a QDockWidget (DW) added to my QMainWindow (MW): I got the DW docked , and when I try to hide it by getting the slider down to the bottom, it is blocked to minimum width. To fix it, it try to set the minimal width of the DW widget to ‘0’. it changes nothing. But when I set it to ‘1’, it works fine. Is this a normal behaviour ? Thanks for your answers :)