Add support for resizing the lab window

Add an observer to the JavaScript code to detect lab size changes
on the LMS page and send the new dimensions to the guacamole client.

hastexo/public/js/client.js

@@ -240,6 +240,10 @@ function HastexoGuacamoleClient(configuration) {
 
         onidle(pause) {
             return pause;
+        },
+
+        sendSize(height, width) {
+            guac_client.sendSize(height, width);
         }
     }
 

hastexo/public/js/main.js

@@ -90,6 +90,15 @@ function HastexoXBlock(runtime, element, configuration) {
         /* Show the terminal.  */
         $("#terminal").append(terminal_element);
 
+        // Observe the lab size in the browser and adjust when necessary
+        var lab = $('#terminal')[0];
+        const resizeObserver = new ResizeObserver(entries => {
+            for (const entry of entries) {
+                terminal_client.sendSize(entry.contentRect.width, entry.contentRect.height);
+            }
+        });
+        resizeObserver.observe(lab);
+
         /* Disconnect on tab close. */
         window.onunload = function() {
             terminal_client.disconnect();