Strange widget border in 256-color terminal

[TomJGooding]

I noticed that the Checkbox widget now has a strange border in urxvt. I assume this is specific to 256-color terminals, as I couldn't replicate the issue in other modern emulators.

Here's screenshots of the checkbox.py example before and after Textual 0.80.0:

Before v0.80.0	After 0.80.0

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[TomJGooding]

After some further testing, I found other widgets also have this issue:

Before v0.80.0	After 0.80.0

[TomJGooding]

Reverting commit 17097e6 seems to fix this issue, although I don't understand why as the only change was reversing the foreground and background colors. This also doesn't explain why this strange border only appears on the left on specific widgets.

[darrenburns]

I can see similar artifacts in iTerm 2 - but only when the app itself does not have focus:

On second thought this may be related to iTerm 2 paints the "dimming overlay" over a terminal window when it loses focus and how that overlay interacts with "reverse" control sequences.

[willmcgugan]

I suspect a bug in urxvt. There was a change in how some borders were rendered recently, but I'm pretty sure urxvt is doing something wrong with the control sequences given.

Will keep the issue open. At some point I'll dig out a linux VM and give it a try.

[TomJGooding]

Interesting, apparently trying to reverse the same background/foreground color does produce unexpected results. I wonder if this is specific to urxvt then!

from rich.console import Console
from rich.style import Style
from rich.text import Text

red_on_red_style = Style(color="red", bgcolor="red")
reversed_style = red_on_red_style + Style(reverse=True)

console = Console()
console.print(Text("Red on red", style=red_on_red_style))
console.print(Text("Reversed", style=reversed_style))

[willmcgugan]

Yeah. It looks like it ignores colours when the reverse style is set!

[TomJGooding]

After some digging into the urxvt CVS, it looks like this was an intentional design decision. Shame as otherwise Textual works well in urxvt, but maybe time to switch to a more modern emulator! Closing.

• text with background==foreground colour gets displayed with default
  bg/fg now when in reverse video, so it can be seen when selecting.

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