Dockwidget stretching

hii.. I have placed QDockWidget on QMainWindow using

mainwindow->addDockWidget(Qt::TopDockWidgetArea, win, Qt::Horizontal);

Now the problem is
If I set width to some maximum extent say 100 and on trying to drag the dockwidget horizontally it stretches upto 100. But if i do the same on height then the dockwidget is extending beyond the value what i have provided in the setMaximumHeight.
For instance if i place the dockwidget vertically the problem gets reverse. Here setting maximum height wont allow the widget to extend the value provided. But its not the case for width, its extends more than the value provided.

Help me to fix this problem for me

Also can i remove those 3 dots present on the dragging side of dockwidget

Thanks

Jayakrishna Reddy