Handle pill deletion

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

src/components/views/rooms/BasicMessageComposer.tsx

@@ -507,6 +507,7 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
             handled = true;
         } else if (event.key === Key.BACKSPACE || event.key === Key.DELETE) {
             this.formatBarRef.current.hide();
+            handled = this.fakeDeletion(event.key === Key.BACKSPACE ? "deleteContentBackward" : "deleteContentForward");
         }
 
         if (handled) {
@@ -515,6 +516,29 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
         }
     };
 
+    /**
+     * Because pills have contentEditable="false" there is no event emitted when
+     * the user tries to delete them. Therefore we need to fake what would
+     * normally happen
+     * @param direction in which to delete
+     * @returns handled
+     */
+    private fakeDeletion(direction: "deleteContentForward" | "deleteContentBackward" ): boolean {
+        const selection = document.getSelection();
+        // Use the default handling for ranges
+        if (selection.type === "Range") return false;
+
+        this.modifiedFlag = true;
+        const { caret, text } = getCaretOffsetAndText(this.editorRef.current, selection);
+
+        // Do the deletion itself
+        if (direction === "deleteContentBackward") caret.offset--;
+        const newText = text.slice(0, caret.offset) + text.slice(caret.offset + 1);
+
+        this.props.model.update(newText, direction, caret);
+        return true;
+    }
+
     private async tabCompleteName(): Promise<void> {
         try {
             await new Promise<void>(resolve => this.setState({ showVisualBell: false }, resolve));