Use MutationObserver to make sure we update when pictures get dragged-on.

Author: nedtwigg

src/lib/enhancers/modifyDOM.ts

@@ -7,7 +7,18 @@ export function fixupOvertype(instances: OverTypeInstance[]): OverTypeInstance {
       `Expected OverType to return exactly 1 instance, got ${instances.length}`
     )
   }
-  return instances[0]!
+  const overtype = instances[0]!
+  // this works, but we're now updating twice as often as we need to, because
+  // overtype has a built-in update which usually works but not always (#101)
+  // and we're doing this which does always work
+  const updateOnChange = new MutationObserver(() => {
+    overtype.updatePreview()
+  })
+  updateOnChange.observe(overtype.textarea, {
+    attributes: true,
+    characterData: true,
+  })
+  return overtype
 }
 
 // Modify the DOM to trick overtype into adopting it instead of recreating it