Resize textareas with their content

This is a feature requiring javascript.
It's not as bad as expected.
/close #56

static/css/style.css

@@ -48,3 +48,10 @@ pre.error-description {
 .expansion-text {
     display: none;
 }
+
+textarea {
+  border: 0 none white;
+  padding: 0;
+  outline: none;
+  background-color: #d0d0d0;
+}

static/js/script.js

@@ -6,10 +6,44 @@ function toggle_expansion() {
     description_element.style.display = new_state;
 };
 
+var max_height = 400;
+function resize_textarea(textarea) {
+    function _inner_resize_textarea() {
+        textarea.style.height = "auto";
+        var new_height = textarea.scrollHeight;
+        var overflow = "hidden";
+        if (new_height > max_height) {
+            new_height = max_height;
+            overflow = "visible";
+        }
+        textarea.style.height = new_height + "px";
+        textarea.style.overflow = overflow;
+    }
+    return _inner_resize_textarea
+}
+function resize_textarea_delayed(textarea) {
+    function _inner_resize_textarea_delayed() {
+        window.setTimeout(resize_textarea(textarea), 0);
+    }
+    return _inner_resize_textarea_delayed;
+}
+
 window.onload=function() {
+    // toggle expansion
     var buttons = document.getElementsByClassName("expansion-button");
     for (var i = 0; i < buttons.length; i++) {
         var button = buttons[i];
         button.onclick = toggle_expansion;
     }
+    // resize textarea
+    var textareas = document.getElementsByTagName("textarea");
+    for (var i = 0; i < textareas.length; i++) {
+        var textarea = textareas[i];
+        textarea.addEventListener("change", resize_textarea(textarea), false);
+        textarea.addEventListener("cut", resize_textarea_delayed(textarea), false);
+        textarea.addEventListener("paste", resize_textarea_delayed(textarea), false);
+        textarea.addEventListener("drop", resize_textarea_delayed(textarea), false);
+        textarea.addEventListener("keydown", resize_textarea_delayed(textarea), false);
+        resize_textarea(textarea)();
+    }
 };