let backspace delete list nodes in RTE

src/components/views/rooms/MessageComposerInput.js

@@ -77,6 +77,10 @@ const ENTITY_TYPES = {
     AT_ROOM_PILL: 'ATROOMPILL',
 };
 
+// the Slate node type to default to for unstyled text when in RTE mode.
+// (we use 'line' for oneliners however)
+const DEFAULT_NODE = 'paragraph';
+
 
 function onSendMessageFailed(err, room) {
     // XXX: temporary logging to try to diagnose
@@ -548,6 +552,8 @@ export default class MessageComposerInput extends React.Component {
         switch (ev.keyCode) {
             case KeyCode.ENTER:
                 return this.handleReturn(ev);
+            case KeyCode.BACKSPACE:
+                return this.onBackspace(ev);
             case KeyCode.UP:
                 return this.onVerticalArrow(ev, true);
             case KeyCode.DOWN:
@@ -562,6 +568,23 @@ export default class MessageComposerInput extends React.Component {
         }
     };
 
+    onBackspace = (ev: Event): boolean => {
+        if (this.state.isRichtextEnabled) {
+            // let backspace exit lists
+            const isList = this.hasBlock('list-item');
+            if (isList) {
+                const change = this.state.editorState.change();
+                change
+                    .setBlocks(DEFAULT_NODE)
+                    .unwrapBlock('bulleted-list')
+                    .unwrapBlock('numbered-list');
+                this.onChange(change);
+                return true;
+            }
+        }
+        return;
+    };
+
     handleKeyCommand = (command: string): boolean => {
         if (command === 'toggle-mode') {
             this.enableRichtext(!this.state.isRichtextEnabled);
@@ -570,8 +593,6 @@ export default class MessageComposerInput extends React.Component {
 
         let newState: ?Value = null;
 
-        const DEFAULT_NODE = 'paragraph';
-
         // Draft handles rich text mode commands by default but we need to do it ourselves for Markdown.
         if (this.state.isRichtextEnabled) {
             const type = command;