Always show twisties for custom views

src/vs/workbench/browser/parts/views/media/views.css

@@ -50,7 +50,8 @@
 	display: none;
 }
 
-.tree-explorer-viewlet-tree-view.file-icon-themable-tree.align-icons-and-twisties .monaco-tree-row:not(.has-children) .content:not(.align-with-twisty)::before {
+.tree-explorer-viewlet-tree-view.file-icon-themable-tree.align-icons-and-twisties .monaco-tree-row:not(.has-children) .content:not(.align-with-twisty)::before,
+.tree-explorer-viewlet-tree-view.file-icon-themable-tree.hide-arrows .monaco-tree-row .content::before {
 	display: inline-block;
 }