fix center align

Author: willmcgugan

src/textual/content.py

@@ -1019,7 +1019,7 @@ def to_strip(self, style: Style) -> Strip:
             start, end = self.highlight_range
             content = content.stylize(self.highlight_style, start, end)
 
-        if align in ("start", "left") or self.line_end:
+        if align in ("start", "left") or (align == "justify" and self.line_end):
             pad_right = width - self.content.cell_length
 
         elif align == "center":

src/textual/screen.py

@@ -640,6 +640,8 @@ def find_widget(self, widget: Widget) -> MapGeometry:
     def clear_selection(self) -> None:
         """Clear any selected text."""
         self.selections = {}
+        self._select_start = None
+        self._select_end = None
 
     def _select_all_in_widget(self, widget: Widget) -> None:
         select_all = SELECT_ALL

src/textual/widget.py

@@ -641,6 +641,7 @@ def _render_widget(self) -> Widget:
 
     @property
     def selection(self) -> Selection | None:
+        """Text selection information, or `None` if no text is selected in this widget."""
         return self.screen.selections.get(self, None)
 
     def _cover(self, widget: Widget) -> None: