I’ve tried to replace the +/- icons in trees with right arrow/down arrow, just like in the trees used at docs.webix.com.
Is there a better way than overriding the CSS rules for .webix_tree_open, .webix_tree_close AND .webix_tree_open:before and webix_tree_close:before? The documentation on datatree css mentions only the first two rules, but because the +/- are displayed as Font Awesome characters, the content of the :before pseudoelement needs to be overridden too.
I left a comment on that datatree CSS page with my solution, but I hope there is a better one.