Signal overwriteToggle event

Issue #2180

Author: WebsiteDeveloper

lib/codemirror.js

@@ -3228,6 +3228,8 @@ window.CodeMirror = (function() {
         this.display.cursor.className += " CodeMirror-overwrite";
       else
         this.display.cursor.className = this.display.cursor.className.replace(" CodeMirror-overwrite", "");
+
+      signal(this, "overwriteToggle", this, this.state.overwrite);
     },
     hasFocus: function() { return document.activeElement == this.display.input; },