Default size seems to be ignored and docks placed always with the fair option.
KDDockWidgets::MainWindow m{"main_window", KDDockWidgets::MainWindowOption_None};
auto d1 = new KDDockWidgets::DockWidget("D1");
auto d2 = new KDDockWidgets::DockWidget("D2");
auto d3 = new KDDockWidgets::DockWidget("D3");
m.addDockWidget(d1, KDDockWidgets::Location_OnLeft, nullptr, QSize(200, 600));
m.addDockWidget(d2, KDDockWidgets::Location_OnRight);
m.addDockWidget(d3, KDDockWidgets::Location_OnBottom);
m.resize(1200, 800);
m.show();
Default size seems to be ignored and docks placed always with the fair option.