When the MainForm of the application is run at the beginning of the session, we sample the size of the client screen and retreive the size to server-side. The size is saved to the ClientSize property of the Form.
If you need to make sure what the current client-size is at the current time and not originally, you can do the following:
* In client side you would need to call from your custom JS function code that would get the window size like Palli described.
* Later that function would create a VWG event on client side, attach the new client size values as the event attributes and finally raise the event, sending it to server-side.
* in server-side you would need to be able to catch this new type of event and handle it to use the values sent from client-side.
For details how to implelement the last two steps, view this thread here, and use steps 3 to 5 as a reference.
Manager of support, the Visual WebGui team