tinyMCEPopup.requireLangPack(); var ExampleDialog = { init : function() { var f = document.forms[0]; // Get the selected contents as text and place it in the input f.someval.value = tinyMCEPopup.editor.selection.getContent({format : 'text'}); f.somearg.value = tinyMCEPopup.getWindowArg('some_custom_arg'); }, insert : function() { // Insert the contents from the input into the document tinyMCEPopup.editor.execCommand('mceInsertContent', false, document.forms[0].someval.value); tinyMCEPopup.close(); } }; tinyMCEPopup.onInit.add(ExampleDialog.init, ExampleDialog);