merge: slab#4511, slab#3573, slab#4614

Author: work-2025

packages/quill/src/core/quill.ts

@@ -231,7 +231,7 @@ class Quill {
     this.theme.addModule('uiNode');
     this.theme.init();
     this.emitter.on(Emitter.events.EDITOR_CHANGE, (type) => {
-      if (type === Emitter.events.TEXT_CHANGE) {
+      if ([Emitter.events.TEXT_CHANGE, Emitter.events.COMPOSITION_START].includes(type)) {
         this.root.classList.toggle('ql-blank', this.editor.isBlank());
       }
     });

packages/quill/src/modules/clipboard.ts

@@ -170,9 +170,9 @@ class Clipboard extends Module<ClipboardOptions> {
 
   onCaptureCopy(e: ClipboardEvent, isCut = false) {
     if (e.defaultPrevented) return;
-    e.preventDefault();
     const [range] = this.quill.selection.getRange();
     if (range == null) return;
+    e.preventDefault();
     const { html, text } = this.onCopy(range, isCut);
     e.clipboardData?.setData('text/plain', text);
     e.clipboardData?.setData('text/html', html);
@@ -350,6 +350,7 @@ function isLine(node: Node, scroll: ScrollBlot) {
     'table',
     'td',
     'tr',
+    'th',
     'ul',
     'video',
   ].includes(node.tagName.toLowerCase());