On 3/18/19, Dennis Lee Bieber <wlfr...@ix.netcom.com> wrote: > On Mon, 18 Mar 2019 14:38:40 -0400, "Malcolm Greene" <pyt...@bdurham.com> > declaimed the following: > >> >>Wondering if there's a way to have my Python scripts ignore these Ctrl+S >> signals or if this behavior is outside of my Python script's control. If >> there's a way to disable this behavior under Windows 10/Windows Server >> 2016, I'm open to that as well. >> > > <ctrl-s>/<ctrl-q> (XOFF/XON) are traditional terminal control codes to > stop/start transmission. The behavior is baked into the console being used.
The Windows console does not really implement XOFF (DC3, Ctrl+S) and XON (DC1, Ctrl+Q) terminal behavior. In line-input mode, it implements Ctrl+S as equivalent to pressing the pause key (i.e. VK_PAUSE, which has the same numeric value as DC3), so it's meant to be familiar to people who are used to working in terminals. But, in contrast to a terminal emulator, there is no requirement to press Ctrl+Q (i.e. DC1) to resume. Almost any key suffices to resume the console, except for the pause key and modifiers (Ctrl, Alt, Shift). In particular, pressing Ctrl+S again, as the original poster did, will resume the Windows console, but it would not resume a terminal emulator. If enabled, the console's extended editing keys feature overrides the default pause behavior of Ctrl+S. It can be enabled via the console's ExtendedEditKey registry value, or in the defaults and properties dialogs by enabling "extended text selection keys". Disabling it also disables immediate access to the console's new text selection keys such as Shift+Arrows, in which case we have to first enter mark mode via Ctrl+M. The default extended-editing keymap doesn't define anything for Ctrl+S, so it's just a DC3 (0x13) character. In principle the extended editing keys can be customized to map Ctrl+S to a virtual key such as VK_PAUSE (i.e. retain the default behavior), but, as far as I know, the binary format of the console's ExtendedEditKeyCustom registry value is not documented. Regardless of the extended editing keys setting, we can always read Ctrl+S via msvcrt.getwch(), since it disables line-input mode. -- https://mail.python.org/mailman/listinfo/python-list
