Composer: Properly update quill state on clipboard cut

ts/quill/signal-clipboard/index.ts

@@ -3,8 +3,11 @@
 
 import type Quill from '@signalapp/quill-cjs';
 import { Delta } from '@signalapp/quill-cjs';
+import { deleteRange } from '@signalapp/quill-cjs/modules/keyboard';
+
 import { FormattingMenu, QuillFormattingStyle } from '../formatting/menu';
 import { insertEmojiOps } from '../util';
+import { createEventHandler } from './util';
 
 type ClipboardOptions = Readonly<{
   isDisabled: boolean;
@@ -19,12 +22,26 @@ export class SignalClipboard {
     this.options = options;
 
     this.quill.root.addEventListener('paste', e => this.onCapturePaste(e));
+    this.quill.root.addEventListener('cut', e => this.onCaptureCut(e));
   }
 
   updateOptions(options: Partial<ClipboardOptions>): void {
     this.options = { ...this.options, ...options };
   }
 
+  onCaptureCut(event: ClipboardEvent): void {
+    const [range] = this.quill.selection.getRange();
+
+    // This updates the clipboard with what we want
+    const handler = createEventHandler({ deleteSelection: true });
+    handler(event);
+
+    // And this updates quill's internal state to reflect the cut
+    if (range) {
+      deleteRange({ range, quill: this.quill });
+    }
+  }
+
   onCapturePaste(event: ClipboardEvent): void {
     if (this.options.isDisabled) {
       return;