GUAC-955: Add guacViewport directive which maintains content within the visible portion of the browser window, even if the browser magically scrolls itself.

guacamole/src/main/webapp/app/client/styles/client.css

@@ -39,7 +39,7 @@ body.client {
 
 .client-view {
     display: table;
-    position: fixed;
+    position: absolute;
     top: 0;
     left: 0;
     width: 100%;