Hi Dilan,
There is a out of the box scroll container available in Mendix.
It also works as a layout element, allowing you to place two grids side by side.
Unfortunately, the scroll container does not play nice with the responsive design layouts that are available. If you are using Sidebar layouts you might need to tweek it a bit before you add you scroll container.
Hope this helps,
Andrej
Modeler
End result
Dilan,
In addition to Scroll Containers, you can also accomplish this with CSS. Apply the following CSS (or simliar) to the Style field on the Common tab of the datagrid properties:
max-height: 250px;
overflow-y: scroll;
overflow-x: hidden;
This will make the grid a box with a height of 250px and a vertical scroll bar. You can make the grid taller or shorter as required in your application by changing the max-height.
Mike
P.S. if you plan to use this technique in many places in your application, you could create a custum css class in your theme.