show update-all button on individual check too

sometimes users may want to check a bunch of styles for updates individually and install the found updates at once

manage.html

@@ -247,7 +247,9 @@
         <label id="only-updates" class="hidden">
           <input type="checkbox"
                  data-filter=".can-update, .update-problem, .update-done"
-                 data-filter-hide=":not(.updatable):not(.update-done), .no-update:not(.update-problem)">
+                 data-filter-hide=":not(.updatable):not(.update-done),
+                                   .no-update:not(.update-problem),
+                                   .updatable:not(.can-update):not(.update-problem):not(.update-done)">
           <svg class="svg-icon checked"><use xlink:href="#svg-icon-checked"/></svg>
           <span i18n-text="manageOnlyUpdates"></span>
         </label>

manage/updater-ui.js

@@ -66,7 +66,6 @@ function checkUpdateAll() {
     if (info.updated) {
       if (++updated === 1) {
         btnApply.disabled = true;
-        btnApply.classList.remove('hidden');
       }
       btnApply.dataset.value = updated;
     }
@@ -179,6 +178,8 @@ function reportUpdateState({updated, style, error, STATES}) {
 
   if (filtersSelector.hide && isCheckAll) {
     filterAndAppend({entry}).then(sorter.updateStripes);
+  } else if (updated && !isCheckAll) {
+    renderUpdatesOnlyFilter();
   }
 }
 
@@ -195,13 +196,8 @@ function renderUpdatesOnlyFilter({show, check} = {}) {
   checkbox.dispatchEvent(new Event('change'));
 
   const btnApply = $('#apply-all-updates');
-  if (!btnApply.matches('.hidden')) {
-    if (numUpdatable > 0) {
-      btnApply.dataset.value = numUpdatable;
-    } else {
-      btnApply.classList.add('hidden');
-    }
-  }
+  btnApply.classList.toggle('hidden', !numUpdatable);
+  btnApply.dataset.value = numUpdatable;
 }