Unsolved QDockWidget resize handle moves only in one direction

[SamerAfach]

I'm developing an program with plugins, so I need QDockWidget. I'm not setting any size policies or anything, and I'm having some asymmetric behavior. The following is how my window looks like:

What I wanna achieve: make the log view smaller (at least by hand, by dragging the slider).

If I put my mouse on the area between the Log view and the two upper widgets, I can move only in 1 direction, which is up. Another even weirder way to demonstrate the problem is if I right-click between the dock widgets and uncheck "Log view" (where the dock widgets interface creates a menu with checkboxes automatically), and then check it again, the Log view widget appears again, but with a different size (depending on the position of the mouse), and possibly smaller. Now I take the slider again, and move it up, and then, again, I can't move it down anymore!!!

The following is my code for creating the Widget:

QDockWidget *MainWindow::createDockWidget(QString windowName,
                                           QWidget *innerWidget,
                                           Qt::DockWidgetArea area) {
  QDockWidget *dock = new QDockWidget(windowName, this);
  dock->setWidget(innerWidget);
  addDockWidget(area, dock);
  dock->setAllowedAreas(Qt::AllDockWidgetAreas);
  return dock;
}

where this is a helper function, and this is how I call it:

modelTreeWidget = new ModelsTreeWidget;

modelsDock = createDockWidget(tr("Models tree"), modelTreeWidget,
                                Qt::LeftDockWidgetArea);
propertiesDock = createDockWidget(tr("Properties view"), new PropertiesWidget,
                                    Qt::RightDockWidgetArea);
auto loggerWidget = new LoggerWidget;
logDock =
createDockWidget(tr("Log view"), loggerWidget, Qt::BottomDockWidgetArea);

I'm using Qt 5.7.1 on Debian Stretch.

[VRonin]

Does the behaviour change if you set a central widget? i.e. call setCentralWidget(new QWidget(this));

[SamerAfach]

@VRonin Thank you, that works. Is this the only way to go? what if I want all the QDockWidgets to fill the screen?