Use mutex for TextBuffer state

examples/editor-orbclient/src/main.rs

@@ -97,11 +97,12 @@ fn main() {
     let mut mouse_left = false;
     let mut rehit = false;
     loop {
+        //TODO: do not use this
+        buffer.shape_until_scroll();
+
         let font_size = buffer.font_size();
         let line_height = buffer.line_height();
 
-        buffer.shape_until_scroll();
-
         if rehit {
             let instant = Instant::now();