fix mask render bug (didn't recreate bind group)

src/core/text/mod.rs

@@ -80,10 +80,24 @@ impl TextView {
         self.tex.as_ref()
     }
     pub fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len {
-        Len::abs(self.render(ctx).size.x)
+        if let Some(hint) = &self.hint
+            && let [line] = &self.buf.lines[..]
+            && line.text().is_empty()
+        {
+            ctx.width(hint)
+        } else {
+            Len::abs(self.render(ctx).size.x)
+        }
     }
     pub fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len {
-        Len::abs(self.render(ctx).size.y)
+        if let Some(hint) = &self.hint
+            && let [line] = &self.buf.lines[..]
+            && line.text().is_empty()
+        {
+            ctx.height(hint)
+        } else {
+            Len::abs(self.render(ctx).size.y)
+        }
     }
     pub fn draw(&mut self, painter: &mut Painter) -> UiRegion {
         let tex = self.render(&mut painter.size_ctx());