QMainwindow,QdockWidget

Hi,every one.
I have a simple QMainWindow with a QDockWidget (view3D,maybe I need to add other QDockWidgets) and a central widget (treewidget).
I hope that the default width of the central widget is not two wide,I set the maxwidth of it, but find that some blank area between QDockWidge and central widget.(show as pictures)
Attachment 6826

I'm not sure I completely understand your question, but if I had to deal with spacing issues, I'd look into my use of layouts and/or spacer items.