Hovering over an empty DataTable row does not reset hover effect

[ThatOtherAndrew]

Have you checked closed issues? https://github.com/Textualize/textual/issues?q=is%3Aissue+is%3Aclosed

Yes, I have.

Please give a brief but clear explanation of the issue. If you can, include a complete working example that demonstrates the bug. Check it can run without modifications.

To reproduce the issue, run the below code and hover the cursor above one of the cells. Then, move the cursor down into the empty space below, and observe how the orange highlighting on the cell persists.

from textual.app import App
from textual.widgets import DataTable

class ExampleApp(App):
    def compose(self):
        table = DataTable()
        table.add_columns('foo', 'bar', 'baz')
        table.add_row('foo', 'bar', 'baz')
        table.styles.height = '100%'
        yield table

ExampleApp().run()

It will be helpful if you run the following command and paste the results:

textual diagnose

Textual Diagnostics

Versions

Name	Value
Textual	0.27.0
Rich	13.4.2

Python

Name	Value
Version	3.11.3
Implementation	CPython
Compiler	MSC v.1934 64 bit (AMD64)
Executable	C:\Users\Andrew\AppData\Local\Programs\Python\Python311\python.exe

Operating System

Name	Value
System	Windows
Release	10
Version	10.0.22621

Terminal

Name	Value
Terminal Application	Windows Terminal
TERM	Not set
COLORTERM	Not set
FORCE_COLOR	Not set
NO_COLOR	Not set

Rich Console options

Name	Value
size	width=120, height=30
legacy_windows	False
min_width	1
max_width	120
is_terminal	True
encoding	utf-8
max_height	30
justify	None
overflow	None
no_wrap	False
highlight	None
markup	None
height	None

Feel free to add screenshots and / or videos. These can be very helpful!

textual_datatable_cursor_hover.mp4

[github-actions]

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

• Why doesn't the DataTable scroll programmatically?

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

[TomJGooding]

I thought this might be a quick fix, but I can't seem to unset the hover cursor similar to when focus leaves the widget.

textual/src/textual/widgets/_data_table.py

Lines 1979 to 1992 in 26573b9

	def _on_mouse_move(self, event: events.MouseMove):
	"""If the hover cursor is visible, display it by extracting the row
	and column metadata from the segments present in the cells."""
	self._set_hover_cursor(True)
	meta = event.style.meta
	if meta and self.show_cursor and self.cursor_type != "none":
	try:
	self.hover_coordinate = Coordinate(meta["row"], meta["column"])
	except KeyError:
	pass
	def _on_leave(self, _: events.Leave) -> None:
	self._set_hover_cursor(False)

A simple workaround would be to set the table height to auto and wrap it inside a container.

[TomJGooding]

I've been looking at this issue again as it feels like it should be such an easy fix.

If the mouse isn't hovering a cell in the table, then there's no meta info. But I can't seem to conditionally unset the hover cursor no matter what I try, so there must be something I'm missing.

@darrenburns do you have any ideas? Sorry I normally wouldn't tag individuals, but it seems like you're the DataTable expert!

[darrenburns]

I think you're looking at the correct code, but there looks like a cacheing bug too, which is preventing the update from being visible.

The cell render cache key doesn't include self._show_hover_cursor, which means subsequent repaints of the cell containing the hover cursor will get the old cached rendered cell (with hover cursor highlighting), regardless of whether self._show_hover_cursor is True or False.

Adding self._show_hover_cursor to the cell render cache_key (inside render_cell), combined with the changes you suggested above, should do the trick.

[github-actions]

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