QDockWidget make left side longer instead of bottom

I'm using QDockWidget on the left and bottom of my UI. But no matter in which order I set them, the bottom one will always cut off the left one.

Is there a way to get the left docker extended to the bottom?

As per the comment you can make use of QMainWindow::setCorner to assign a corner to a particular dock area. In your case you need...

setCorner(Qt::BottomLeftCorner, Qt::LeftDockWidgetArea);