init search on page feature once

src/app/browser/window/tab/item/page/search/buffer.rs

@@ -0,0 +1,25 @@
+mod tag;
+
+use tag::Tag;
+
+use gtk::{prelude::TextBufferExt, TextBuffer};
+
+pub struct Buffer {
+    pub text_buffer: TextBuffer,
+    pub tag: Tag,
+}
+
+impl Buffer {
+    // Constructors
+
+    /// Create new `Self`
+    pub fn new(text_buffer: TextBuffer) -> Self {
+        // Init components
+        // * create new tag objects required for new buffer,
+        //   instead of re-use existing refs (maybe the bug)
+        let tag = Tag::new(text_buffer.tag_table());
+
+        // Init `Self`
+        Self { text_buffer, tag }
+    }
+}