Prompt the user to open a file on the left if no doc is open

services/web/app/views/project/editor/editor.jade

@@ -10,8 +10,12 @@ div.full-size(
 )
 	.ui-layout-center
 		.loading-panel(ng-show="!editor.sharejs_doc || editor.opening")
-			i.fa.fa-spin.fa-refresh
-			|   #{translate("loading")}...
+			span(ng-show="editor.open_doc_id")
+				i.fa.fa-spin.fa-refresh
+				|   #{translate("loading")}...
+			span(ng-show="!editor.open_doc_id")
+				i.fa.fa-arrow-left
+				|   #{translate("open_a_file_on_the_left")}
 
 		#editor(
 			ace-editor="editor",