style(ckeditor5/codeblock): limit language selector height

packages/ckeditor5/src/index.ts

@@ -1,4 +1,5 @@
 import "ckeditor5/ckeditor5.css";
+import "./theme/code_block_toolbar.css";
 import { COMMON_PLUGINS, CORE_PLUGINS, POPUP_EDITOR_PLUGINS } from "./plugins";
 import { BalloonEditor, DecoupledEditor, FindAndReplaceEditing, FindCommand } from "ckeditor5";
 export { EditorWatchdog } from "ckeditor5";

packages/ckeditor5/src/plugins/code_block_toolbar.ts

@@ -18,6 +18,7 @@ export default class CodeBlockToolbar extends Plugin {
                 "|",
                 "copyToClipboard"
             ],
+            balloonClassName: "ck-toolbar-container codeblock-language-list",
             getRelatedElement(selection) {
                 const selectionPosition = selection.getFirstPosition();
                 if (!selectionPosition) {

packages/ckeditor5/src/theme/code_block_toolbar.css

@@ -0,0 +1,4 @@
+.ck.ck-balloon-panel.codeblock-language-list .ck-dropdown__panel {
+    max-height: 300px;
+    overflow-y: auto;
+}