--- a/s4-main.js	Mon May 11 19:46:57 2020 +0900
+++ b/s4-main.js	Mon May 11 20:08:29 2020 +0900
@@ -54,7 +54,13 @@
 	    textarea.value = lines.join("\n");
 	}
     }
-    function init() {
+    function reverseChecks() {
+	var names = collectElementsByNameAttr("input", "usel");
+	for (let u of names) {
+	    u.checked = !u.checked;
+	}
+    }
+    function initBlogs() {
 	var el, check = collectElementsByNameAttr("input", "notifyto");
 	if (check)
 	    for (let i of check) {
@@ -65,5 +71,16 @@
 		if (RegExp.lastMatch == i.innerHTML)
 		    i.addEventListener("click", insertRedirect, null)
     }
+    function initGrpAction() {
+	var rev = document.getElementById("reverse");
+	if (rev && rev.tagName.match(/span/i)) {
+	    rev.textContent = " 反転 ";
+	    rev.addEventListener("click", reverseChecks, null);
+	}
+    }
+    function init() {
+	initGrpAction();
+	initBlogs();
+    }
     document.addEventListener('DOMContentLoaded', init, null);
 })();