toggle_sidebar: switch icon on click

plugins/toggle_sidebar/init.js

@@ -0,0 +1,9 @@
+Plugins.Toggle_Sidebar = {
+    toggle: function() {
+        Feeds.toggle();
+
+        const label = document.querySelector("i.toggle-sidebar-label");
+
+        label.innerHTML = Element.visible("feeds-holder") ? 'chevron_left' : 'chevron_right';
+    }
+};

plugins/toggle_sidebar/init.php

@@ -15,12 +15,16 @@ class Toggle_Sidebar extends Plugin {
 		$host->add_hook($host::HOOK_MAIN_TOOLBAR_BUTTON, $this);
 	}
 
+	function get_js() {
+		return file_get_contents(__DIR__ . "/init.js");
+	}
+
 	function hook_main_toolbar_button() {
 		?>
 
-		<button dojoType="dijit.form.Button" onclick="Feeds.toggle()">
-			<i class="material-icons"
-               title="<?php echo __('Toggle feedlist') ?>">menu</i>
+		<button dojoType="dijit.form.Button" onclick="Plugins.Toggle_Sidebar.toggle(this)">
+			<i class="material-icons toggle-sidebar-label"
+               title="<?php echo __('Toggle sidebar') ?>">chevron_left</i>
 		</button>
 
 		<?php