revert widget trait

packages/tui/src/render.rs

@@ -43,7 +43,7 @@ pub(crate) fn render_vnode(
             }
 
             impl<'a> RinkWidget for Label<'a> {
-                fn render(self, area: Rect, buf: &mut RinkBuffer) {
+                fn render(self, area: Rect, mut buf: RinkBuffer) {
                     for (i, c) in self.text.char_indices() {
                         let mut new_cell = RinkCell::default();
                         new_cell.set_style(self.style);
@@ -81,7 +81,7 @@ pub(crate) fn render_vnode(
 }
 
 impl RinkWidget for &Node {
-    fn render(self, area: Rect, mut buf: &mut RinkBuffer<'_>) {
+    fn render(self, area: Rect, mut buf: RinkBuffer<'_>) {
         use tui::symbols::line::*;
 
         enum Direction {