don't open sidebar at install

manifest.json

@@ -91,7 +91,8 @@
 	"sidebar_action": {
 		"default_title": "SingleFile options",
 		"default_panel": "extension/ui/pages/options.html#side-panel",
-		"default_icon": "extension/ui/resources/icon_128.png"
+		"default_icon": "extension/ui/resources/icon_128.png",
+		"open_at_install": false
 	},
 	"options_ui": {
 		"browser_style": true,