remove plus one

Author: willmcgugan

src/textual/app.py

@@ -1531,7 +1531,6 @@ def copy_to_clipboard(self, text: str) -> None:
         self._clipboard = text
         if self._driver is None:
             return
-
         import base64
 
         base64_text = base64.b64encode(text.encode("utf-8")).decode("utf-8")

src/textual/content.py

@@ -256,7 +256,7 @@ def get_span(y: int) -> tuple[int, int] | None:
                 start, end = span
                 if end == -1:
                     end = len(line.plain)
-                line = line.stylize(selection_style, start, end + 1)
+                line = line.stylize(selection_style, start, end)
 
             content_line = FormattedLine(
                 line.expand_tabs(tab_size), width, y=y, align=align