Windows: Mouse input may stop working due to console mode handling in enable_application_mode()

[pkellyuk]

Summary

I've been investigating an issue where mouse input stops working in Textual apps on Windows. I think I may have found something in enable_application_mode(), but I'm not entirely sure - would appreciate someone more familiar with the Windows console handling taking a look.

What I'm Seeing

Mouse selection and scrollbar interaction stop working shortly after a Textual app starts on Windows. The console mode flags for mouse input seem to get lost.

Where I Think the Issue Might Be

Looking at src/textual/drivers/win32.py in enable_application_mode():

set_console_mode(
    terminal_out, current_console_mode_out | ENABLE_VIRTUAL_TERMINAL_PROCESSING
)
set_console_mode(terminal_in, ENABLE_VIRTUAL_TERMINAL_INPUT)

I noticed that for stdout, existing flags are preserved with |, but for stdin it seems to just set ENABLE_VIRTUAL_TERMINAL_INPUT directly?

If I'm reading this correctly, wouldn't this overwrite any existing flags like ENABLE_MOUSE_INPUT (0x0010) and ENABLE_EXTENDED_FLAGS (0x0080)?

Possible Fix (if my analysis is correct)

Maybe the stdin line should be:

set_console_mode(terminal_in, current_console_mode_in | ENABLE_VIRTUAL_TERMINAL_INPUT)

Similar to how stdout is handled?

Reproduction

I've been testing with a stress test that monitors console mode flags. The corruption happens consistently within ~150ms on Windows 11.

Environment

• Windows 11
• Windows Terminal
• Textual (latest)

I could be completely wrong about this - just trying to help track down the issue. Let me know if you need any more information!

[github-actions]

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

• Why do some key combinations never make it to my app?
• How do I center a widget in a screen?
• How do I pass arguments to an app?

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This is an automated reply, generated by FAQtory

[TomJGooding]

I don't see any issues with mouse input after running py -m textual on Windows.

Could you provide more detail how to reproduce this?

[pkellyuk]

Hi @TomJGooding, here's a minimal reproduction script:

"""Minimal reproduction of Textual Windows console mode bug."""
import ctypes
import sys

if sys.platform != "win32":
    print("This test is Windows-only")
    sys.exit(1)

kernel32 = ctypes.windll.kernel32
STD_INPUT_HANDLE = -10
ENABLE_MOUSE_INPUT = 0x0010
ENABLE_EXTENDED_FLAGS = 0x0080

def get_stdin_mode():
    handle = kernel32.GetStdHandle(STD_INPUT_HANDLE)
    mode = ctypes.c_ulong()
    kernel32.GetConsoleMode(handle, ctypes.byref(mode))
    return mode.value

def set_stdin_mode(mode):
    handle = kernel32.GetStdHandle(STD_INPUT_HANDLE)
    kernel32.SetConsoleMode(handle, mode)

# Get initial mode and add mouse flags
initial = get_stdin_mode()
set_stdin_mode(initial | ENABLE_MOUSE_INPUT | ENABLE_EXTENDED_FLAGS)

print(f"1. After setting mouse flags: stdin=0x{get_stdin_mode():04x}")
print(f"   ENABLE_MOUSE_INPUT: {'YES' if get_stdin_mode() & ENABLE_MOUSE_INPUT else 'NO'}")

# Import and call Textual's enable_application_mode
from textual.drivers.win32 import enable_application_mode
restore = enable_application_mode()

print(f"2. After Textual init:        stdin=0x{get_stdin_mode():04x}")
print(f"   ENABLE_MOUSE_INPUT: {'YES' if get_stdin_mode() & ENABLE_MOUSE_INPUT else 'NO'}")

if not (get_stdin_mode() & ENABLE_MOUSE_INPUT):
    print("\n** BUG CONFIRMED: Mouse input flag was lost! **")

restore()

Run this directly in a Windows terminal (not through a subprocess). Expected output:

1. After setting mouse flags: stdin=0x0097
   ENABLE_MOUSE_INPUT: YES
2. After Textual init:        stdin=0x0200
   ENABLE_MOUSE_INPUT: NO

** BUG CONFIRMED: Mouse input flag was lost! **

The issue is on line 71 of win32.py:

set_console_mode(terminal_in, ENABLE_VIRTUAL_TERMINAL_INPUT)

This overwrites all flags. Compare to line 68-70 which correctly preserves flags for stdout:

set_console_mode(
    terminal_out, current_console_mode_out | ENABLE_VIRTUAL_TERMINAL_PROCESSING
)

[TomJGooding]

Setting ENABLE_VIRTUAL_TERMINAL_INPUT converts user input into VT sequences. Textual processes these sequences to handle the mouse events.

If the mouse isn't working for you, further details about how to reproduce the issue and your environment would be helpful.

I can't reproduce this and I would expect more people reporting this issue if the mouse truly didn't work on Windows!

[github-actions]

I hope I solved your issue!

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• Will McGugan