diff --git a/CHANGELOG.md b/CHANGELOG.md
index e565bd20c..7f2a07846 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Added Console.bell method
 - Added Set to types that Console.print will automatically pretty print
+- Added show_locals to Traceback
+- Added theme stack mechanism, see Console.push_theme and Console.pop_theme
 
 ### Changed
 
diff --git a/pyproject.toml b/pyproject.toml
index 62dd26ba0..814d92e07 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,7 @@
 name = "rich"
 homepage = "https://github.com/willmcgugan/rich"
 documentation = "https://rich.readthedocs.io/en/latest/"
-version = "7.1.0"
+version = "8.0.0"
 description = "Render rich text, tables, progress bars, syntax highlighting, markdown and more to the terminal"
 authors = ["Will McGugan <willmcgugan@gmail.com>"]
 license = "MIT"
@@ -37,5 +37,5 @@ jupyter = ["ipywidgets"]
 [tool.poetry.dev-dependencies]
 
 [build-system]
-requires = ["poetry-core>=1.0.0a9"]
-build-backend = "poetry.core.masonry.api"
+requires = ["poetry-core>=1.0.0"]
+build-backend = "poetry.core.masonry.api"
\ No newline at end of file
diff --git a/requirements-dev.txt b/requirements-dev.txt
index c98a42695..155048478 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,5 +1,5 @@
 black==20.8b1
 mypy==0.782
 poetry==1.0.10
-pytest==5.4.3
+pytest==6.1.0
 pytest-cov==2.10.1
diff --git a/rich/__init__.py b/rich/__init__.py
index d0f82dd88..80c9b61d5 100644
--- a/rich/__init__.py
+++ b/rich/__init__.py
@@ -10,7 +10,8 @@
 
 
 def get_console() -> "Console":
-    """Get a global Console instance.
+    """Get a global :class:`~rich.console.Console` instance. This function is used when Rich requires a Console,
+    and hasn't been explicitly given one.
 
     Returns:
         Console: A console instance.
@@ -31,6 +32,16 @@ def print(
     file: IO[str] = None,
     flush: bool = False,
 ):
+    """Print object(s) supplied via positional arguments. This function has an identical signature
+    to the built-in print. For more advanced features, see the :class:`~rich.console.Console` class.
+
+    Args:
+        sep (str, optional): Separator between printed objects. Defaults to " ".
+        end (str, optional): Character to write at end of output. Defaults to "\n".
+        file (IO[str], optional): File to write to, or None for stdout. Defaults to None.
+        flush (bool, optional): Has no effect as Rich always flushes output.. Defaults to False.
+
+    """
     from .console import Console
 
     write_console = get_console() if file is None else Console(file=file)
diff --git a/rich/console.py b/rich/console.py
index d21dd6847..f9847d2e4 100644
--- a/rich/console.py
+++ b/rich/console.py
@@ -41,7 +41,7 @@
 from .style import Style
 from .terminal_theme import DEFAULT_TERMINAL_THEME, TerminalTheme
 from .text import Text, TextType
-from .theme import Theme
+from .theme import Theme, ThemeStack
 
 if TYPE_CHECKING:
     from ._windows import WindowsConsoleFeatures
@@ -182,6 +182,22 @@ def get(self) -> str:
         return self._result
 
 
+class ThemeContext:
+    """A context manager to use a temporary theme. See :meth:`~rich.console.Console.theme` for usage."""
+
+    def __init__(self, console: "Console", theme: Theme, inherit: bool = True) -> None:
+        self.console = console
+        self.theme = theme
+        self.inherit = inherit
+
+    def __enter__(self) -> "ThemeContext":
+        self.console.push_theme(self.theme)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
+        self.console.pop_theme()
+
+
 class RenderGroup:
     """Takes a group of renderables and returns a renderable object that renders the group.
 
@@ -372,7 +388,7 @@ def __init__(
         if self.is_jupyter:
             width = width or 93
             height = height or 100
-        self._styles = themes.DEFAULT.styles if theme is None else theme.styles
+        self._theme_stack = ThemeStack(themes.DEFAULT if theme is None else theme)
         self._width = width
         self._height = height
         self.tab_size = tab_size
@@ -498,6 +514,33 @@ def end_capture(self) -> str:
         self._exit_buffer()
         return render_result
 
+    def push_theme(self, theme: Theme, inherit: bool = True) -> None:
+        """Push a new theme on to the top of the stack, overwriting the styles from the previous theme.
+        Generally speaking, you call :meth:`~rich.console.Console.theme` to get a context manager, rather
+        than calling this method directly.
+
+        Args:
+            theme (Theme): A theme instance.
+            inherit (bool, optional): Inherit existing styles. Defaults to True.
+        """
+        self._theme_stack.push_theme(theme, inherit=inherit)
+
+    def pop_theme(self) -> None:
+        """Remove theme from top of stack, restoring previous theme."""
+        self._theme_stack.pop_theme()
+
+    def theme(self, theme: Theme, inherit: bool = True) -> ThemeContext:
+        """Use a new temporary theme for the duration of the context manager.
+
+        Args:
+            theme (Theme): Theme instance to user.
+            inherit (bool, optional): Inherit existing styles. Defaults to True.
+
+        Returns:
+            ThemeContext: [description]
+        """
+        return ThemeContext(self, theme, inherit)
+
     @property
     def color_system(self) -> Optional[str]:
         """Get color system string.
@@ -785,7 +828,7 @@ def get_style(
             return name
 
         try:
-            style = self._styles.get(name)
+            style = self._theme_stack.get(name)
             if style is None:
                 style = Style.parse(name)
             return style.copy() if style.link else style
diff --git a/rich/progress.py b/rich/progress.py
index 72ec5e7b8..66fb35aff 100644
--- a/rich/progress.py
+++ b/rich/progress.py
@@ -75,6 +75,7 @@ def run(self) -> None:
             if last_completed != completed:
                 advance(task_id, completed - last_completed)
                 last_completed = completed
+
         self.progress.update(self.task_id, completed=self.completed, refresh=True)
 
     def __enter__(self) -> "_TrackThread":
@@ -780,7 +781,7 @@ def advance(self, task_id: TaskID, advance: float = 1) -> None:
             popleft = _progress.popleft
             while _progress and _progress[0].timestamp < old_sample_time:
                 popleft()
-            while len(_progress) > 10:
+            while len(_progress) > 1000:
                 popleft()
             _progress.append(ProgressSample(current_time, update_completed))
 
diff --git a/rich/theme.py b/rich/theme.py
index 14bf011c9..c8dccf269 100644
--- a/rich/theme.py
+++ b/rich/theme.py
@@ -1,5 +1,5 @@
 import configparser
-from typing import IO, Mapping
+from typing import Dict, List, IO, Mapping, Optional
 
 from .default_styles import DEFAULT_STYLES
 from .style import Style, StyleType
@@ -9,10 +9,12 @@ class Theme:
     """A container for style information, used by :class:`~rich.console.Console`.
 
     Args:
-        styles (Dict[str, Style], optional): A mapping of style names on to styles. Defaults to None for empty styles.
+        styles (Dict[str, Style], optional): A mapping of style names on to styles. Defaults to None for a theme with no styles.
         inherit (bool, optional): Inherit default styles. Defaults to True.
     """
 
+    styles: Dict[str, Style]
+
     def __init__(self, styles: Mapping[str, StyleType] = None, inherit: bool = True):
         self.styles = DEFAULT_STYLES.copy() if inherit else {}
         if styles is not None:
@@ -66,6 +68,44 @@ def read(cls, path: str, inherit: bool = True) -> "Theme":
             return cls.from_file(config_file, source=path, inherit=inherit)
 
 
+class ThemeStackError(Exception):
+    """Base exception for errors related to the theme stack."""
+
+
+class ThemeStack:
+    """A stack of themes.
+
+    Args:
+        theme (Theme): A theme instance
+    """
+
+    def __init__(self, theme: Theme) -> None:
+        self._entries: List[Dict[str, Style]] = [theme.styles]
+        self.get = self._entries[-1].get
+
+    def push_theme(self, theme: Theme, inherit: bool = True) -> None:
+        """Push a theme on the top of the stack.
+
+        Args:
+            theme (Theme): A Theme instance.
+            inherit (boolean, optional): Inherit styles from current top of stack.
+        """
+        styles: Dict[str, Style]
+        if inherit:
+            styles = {**self._entries[-1], **theme.styles}
+        else:
+            styles = theme.styles.copy()
+        self._entries.append(styles)
+        self.get = self._entries[-1].get
+
+    def pop_theme(self) -> None:
+        """Pop (and discard) the top-most theme."""
+        if len(self._entries) == 1:
+            raise ThemeStackError("Unable to pop base theme")
+        self._entries.pop()
+        self.get = self._entries[-1].get
+
+
 if __name__ == "__main__":  # pragma: no cover
     theme = Theme()
     print(theme.config)
diff --git a/rich/traceback.py b/rich/traceback.py
index 93b61e094..215ef5330 100644
--- a/rich/traceback.py
+++ b/rich/traceback.py
@@ -7,6 +7,7 @@
 from types import TracebackType
 from typing import Any, Callable, Dict, List, Optional, Type
 
+from pygments.lexers import guess_lexer_for_filename
 from pygments.token import Token, String, Name, Number
 
 from ._loop import loop_first, loop_last
@@ -335,6 +336,24 @@ def _render_syntax_error(
     def _render_stack(self, stack: Stack, styles: Dict[str, Style]) -> RenderResult:
         path_highlighter = PathHighlighter()
         theme = self.theme
+        code_cache: Dict[str, str] = {}
+
+        def read_code(filename: str) -> str:
+            """Read files, and cache results on filename.
+
+            Args:
+                filename (str): Filename to read
+
+            Returns:
+                str: Contents of file
+            """
+            code = code_cache.get(filename)
+            if code is None:
+                with open(filename, "rt") as code_file:
+                    code = code_file.read()
+                code_cache[filename] = code
+            return code
+
         for first, frame in loop_first(stack.frames):
             text = Text.assemble(
                 path_highlighter(Text(frame.filename, style=styles["string"])),
@@ -350,8 +369,12 @@ def _render_stack(self, stack: Stack, styles: Dict[str, Style]) -> RenderResult:
             if frame.filename.startswith("<"):
                 continue
             try:
-                syntax = Syntax.from_path(
-                    frame.filename,
+                code = read_code(frame.filename)
+                lexer = guess_lexer_for_filename(frame.filename, code)
+                lexer_name = lexer.name
+                syntax = Syntax(
+                    code,
+                    lexer_name,
                     theme=theme,
                     line_numbers=True,
                     line_range=(
@@ -366,16 +389,17 @@ def _render_stack(self, stack: Stack, styles: Dict[str, Style]) -> RenderResult:
             except Exception:
                 pass
             else:
-                if frame.locals:
-                    yield Columns(
+                yield (
+                    Columns(
                         [
                             syntax,
                             render_scope(frame.locals, title="locals"),
                         ],
                         padding=1,
                     )
-                else:
-                    yield syntax
+                    if frame.locals
+                    else syntax
+                )
 
 
 if __name__ == "__main__":  # pragma: no cover
diff --git a/tests/test_logging.py b/tests/test_logging.py
index ee03c3c13..566c6859f 100644
--- a/tests/test_logging.py
+++ b/tests/test_logging.py
@@ -25,19 +25,6 @@
 )
 
 
-def make_log():
-    log.debug("foo")
-    render = handler.console.file.getvalue()
-    return render
-
-
-def test_log():
-    render = make_log()
-    print(repr(render))
-    expected = "\x1b[2;36m[DATE]\x1b[0m\x1b[2;36m \x1b[0m\x1b[32mDEBUG\x1b[0m    foo                                           \x1b[2mtest_logging.py\x1b[0m\x1b[2m:29\x1b[0m\n"
-    assert render == expected
-
-
 @skip_win
 def test_exception():
     console = Console(