NoWidget error when mouse dragged outside terminal window

[TomJGooding]

This is with Textual v0.43.2. To reproduce, with the app below grab the scrollbar with the mouse and then try quickly moving to the end of the document. It seems when the mouse is outside the terminal window, it will crash with a NoWidget error.

from textual.app import App, ComposeResult
from textual.containers import VerticalScroll
from textual.widgets import Markdown

TEXT = """I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past, I will turn the inner eye to see its path.
Where the fear has gone there will be nothing. Only I will remain."""


class ExampleApp(App):
    def compose(self) -> ComposeResult:
        with VerticalScroll():
            yield (Markdown(TEXT * 100))


if __name__ == "__main__":
    app = ExampleApp()
    app.run()

Traceback

╭───────────────────── Traceback (most recent call last) ──────────────────────╮
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textua │
│ l/app.py:2703 in on_event                                                    │
│                                                                              │
│   2700 │   │   │   │                                                         │
│   2701 │   │   │   │   if isinstance(event, events.MouseUp):                 │
│   2702 │   │   │   │   │   if self._mouse_down_widget is not None and (      │
│ ❱ 2703 │   │   │   │   │   │   self.get_widget_at(event.x, event.y)[0]       │
│   2704 │   │   │   │   │   │   is self._mouse_down_widget                    │
│   2705 │   │   │   │   │   ):                                                │
│   2706 │   │   │   │   │   │   click_event = events.Click.from_event(event)  │
│                                                                              │
│ ╭──────────────────────────── locals ────────────────────────────╮           │
│ │ event = MouseUp(x=87, y=35, button=1)                          │           │
│ │  self = ExampleApp(title='ExampleApp', classes={'-dark-mode'}) │           │
│ ╰────────────────────────────────────────────────────────────────╯           │
│                                                                              │
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textua │
│ l/app.py:2609 in get_widget_at                                               │
│                                                                              │
│   2606 │   │   Returns:                                                      │
│   2607 │   │   │   The widget and the widget's screen region.                │
│   2608 │   │   """                                                           │
│ ❱ 2609 │   │   return self.screen.get_widget_at(x, y)                        │
│   2610 │                                                                     │
│   2611 │   def bell(self) -> None:                                           │
│   2612 │   │   """Play the console 'bell'.                                   │
│                                                                              │
│ ╭─────────────────────────── locals ────────────────────────────╮            │
│ │ self = ExampleApp(title='ExampleApp', classes={'-dark-mode'}) │            │
│ │    x = 87                                                     │            │
│ │    y = 35                                                     │            │
│ ╰───────────────────────────────────────────────────────────────╯            │
│                                                                              │
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textua │
│ l/screen.py:289 in get_widget_at                                             │
│                                                                              │
│    286 │   │   Returns:                                                      │
│    287 │   │   │   Widget and screen region.                                 │
│    288 │   │   """                                                           │
│ ❱  289 │   │   return self._compositor.get_widget_at(x, y)                   │
│    290 │                                                                     │
│    291 │   def get_widgets_at(self, x: int, y: int) -> Iterable[tuple[Widget │
│    292 │   │   """Get all widgets under a given coordinate.                  │
│                                                                              │
│ ╭─────────── locals ───────────╮                                             │
(.venv) [tom@arch textual-sandbox]$ textual --version
textual, version 0.43.2
(.venv) [tom@arch textual-sandbox]$ textual run no_widget_scroll_bug.py 
╭──────────────────────────────────────────────────────────── Traceback (most recent call last) ─────────────────────────────────────────────────────────────╮
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textual/app.py:2704 in on_event                                                      │
│                                                                                                                                                            │
│   2701 │   │   │   │                                                                                                                                       │
│   2702 │   │   │   │   if isinstance(event, events.MouseUp):                                                                                               │
│   2703 │   │   │   │   │   if self._mouse_down_widget is not None and (                                                                                    │
│ ❱ 2704 │   │   │   │   │   │   self.get_widget_at(event.x, event.y)[0]                                                                                     │
│   2705 │   │   │   │   │   │   is self._mouse_down_widget                                                                                                  │
│   2706 │   │   │   │   │   ):                                                                                                                              │
│   2707 │   │   │   │   │   │   click_event = events.Click.from_event(event)                                                                                │
│                                                                                                                                                            │
│ ╭──────────────────────────── locals ────────────────────────────╮                                                                                         │
│ │ event = MouseUp(x=161, y=39, button=1)                         │                                                                                         │
│ │  self = ExampleApp(title='ExampleApp', classes={'-dark-mode'}) │                                                                                         │
│ ╰────────────────────────────────────────────────────────────────╯                                                                                         │
│                                                                                                                                                            │
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textual/app.py:2610 in get_widget_at                                                 │
│                                                                                                                                                            │
│   2607 │   │   Returns:                                                                                                                                    │
│   2608 │   │   │   The widget and the widget's screen region.                                                                                              │
│   2609 │   │   """                                                                                                                                         │
│ ❱ 2610 │   │   return self.screen.get_widget_at(x, y)                                                                                                      │
│   2611 │                                                                                                                                                   │
│   2612 │   def bell(self) -> None:                                                                                                                         │
│   2613 │   │   """Play the console 'bell'.                                                                                                                 │
│                                                                                                                                                            │
│ ╭─────────────────────────── locals ────────────────────────────╮                                                                                          │
│ │ self = ExampleApp(title='ExampleApp', classes={'-dark-mode'}) │                                                                                          │
│ │    x = 161                                                    │                                                                                          │
│ │    y = 39                                                     │                                                                                          │
│ ╰───────────────────────────────────────────────────────────────╯                                                                                          │
│                                                                                                                                                            │
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textual/screen.py:289 in get_widget_at                                               │
│                                                                                                                                                            │
│    286 │   │   Returns:                                                                         ╭─────────── locals ───────────╮                           │
│    287 │   │   │   Widget and screen region.                                                    │ self = Screen(id='_default') │                           │
│    288 │   │   """                                                                              │    x = 161                   │                           │
│ ❱  289 │   │   return self._compositor.get_widget_at(x, y)                                      │    y = 39                    │                           │
│    290 │                                                                                        ╰──────────────────────────────╯                           │
│    291 │   def get_widgets_at(self, x: int, y: int) -> Iterable[tuple[Widget, Region]]:                                                                    │
│    292 │   │   """Get all widgets under a given coordinate.                                                                                                │
│                                                                                                                                                            │
│ /home/tom/Projects/textual-sandbox/.venv/lib/python3.11/site-packages/textual/_compositor.py:787 in get_widget_at                                          │
│                                                                                                                                                            │
│    784 │   │   │   for widget, cropped_region, region in self.layers_visible[y]:                                                                           │
│    785 │   │   │   │   if contains(cropped_region, x, y) and widget.visible:                                                                               │
│    786 │   │   │   │   │   return widget, region                                                                                                           │
│ ❱  787 │   │   raise errors.NoWidget(f"No widget under screen coordinate ({x}, {y})")                                                                      │
│    788 │                                                                                                                                                   │
│    789 │   def get_widgets_at(self, x: int, y: int) -> Iterable[tuple[Widget, Region]]:                                                                    │
│    790 │   │   """Get all widgets under a given coordinate.                                                                                                │
│                                                                                                                                                            │
│ ╭────────────────────────────────────────────────────────────────── locals ──────────────────────────────────────────────────────────────────╮             │
│ │       contains = <function Region.contains at 0x7f7b2474b2e0>                                                                              │             │
│ │ cropped_region = Region(x=0, y=0, width=158, height=45)                                                                                    │             │
│ │         region = Region(x=0, y=0, width=158, height=45)                                                                                    │             │
│ │           self = <Compositor                                                                                                               │             │
│ │                  │   size=Size(width=158, height=45)                                                                                       │             │
│ │                  │   widgets={                                                                                                             │             │
│ │                  │   │   VerticalScroll(),                                                                                                 │             │
│ │                  │   │   Markdown(),                                                                                                       │             │
│ │                  │   │   MarkdownParagraph(),                                                                                              │             │
│ │                  │   │   Screen(id='_default'),                                                                                            │             │
│ │                  │   │   ToastRack(id='textual-toastrack')                                                                                 │             │
│ │                  │   }                                                                                                                     │             │
│ │                  >                                                                                                                         │             │
│ │         widget = Screen(id='_default')                                                                                                     │             │
│ │              x = 161                                                                                                                       │             │
│ │              y = 39                                                                                                                        │             │
│ ╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯             │
╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
NoWidget: No widget under screen coordinate (161, 39)

[github-actions]

We found the following entry in the FAQ which you may find helpful:

• No widget called TextLog

Feel free to close this issue if you found an answer in the FAQ. Otherwise, please give us a little time to review.

This is an automated reply, generated by FAQtory

[willmcgugan]

Thanks. What terminal is that?

I can't reproduce it. But I can see why it would happen. But it looks like the terminal is generating coords outside of the window, which iTerm doesn't seem to do.

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.

[willmcgugan]

0.44.0 should fix that, but if you wouldn't mind giving it a shot to check...

[TomJGooding]

Thanks Will, looks like that has fixed it!