Bug: Undo and Redo Keyboard shortcuts not working as expected (CUA standard)

[maddes8cht]

Bug: Undo and Redo shortcuts ctrl-z and ctrl-y not behaving as expected

Description

I really appreciate Turbo's commitment to implementing the CUA (Common User Access) standard in a terminal editor — especially the top menu bar and familiar shortcuts. Most of the standard editing shortcuts (Cut, Copy, Paste) work perfectly with their expected keybindings (e.g., Ctrl+X, Ctrl+C, Ctrl+V).

However, there seems to be an inconsistency with the Undo and Redo shortcuts:

• Ctrl+Z does not trigger an undo. The action only works when using the menu: Edit > Undo.
• Ctrl+Y only works when combined with Shift, i.e., Ctrl+Shift+Y is required. This is not in line with the CUA standard where Ctrl+Y (without Shift) should perform Redo.

This breaks expectations for users familiar with common editors, and also creates inconsistency within Turbo itself, where all other CUA shortcuts behave correctly.

Expected behavior

• Ctrl+Z should perform Undo.
• Ctrl+Y (without Shift) should perform Redo.

Actual behavior

• Ctrl+Z does nothing.
• Ctrl+Y does not work unless Shift is also pressed.

Environment

• Terminal: VSCode integrated terminal / Windows Terminal
• OS: Windows 10 / 11 (tested on both)
• Turbo version: lates currently available build from actions

[magiblot]

Hi @maddes8cht!

Thank you very much for the detailed report. What you described is of course not the intended behaviour.

I suspect that VSCode's terminal may not be propagating Ctrl+Z and Ctrl+Y to the application running in it. If that's the case, I'm not sure Turbo can do anything about it. But it could also be that Turbo is not reading these key presses properly.

To verify this, it would be very helpful if you could do the following:

1. Inside the VSCode terminal, run the tvdemo.exe application from Turbo Vision (you can get it from the GitHub Actions artifacts).
2. Open the event viewer (top-left menu (≡) > Event Viewer, or Alt+0).
3. Press Ctrl+Z and Ctrl+Y, and share a screenshot if anything is displayed.

Cheers.

[maddes8cht]

Okay, i will do this, BUT:
This is obviously not a VSCode related Problem:
It also happens (for me) in Windows Terminal, in the original conhost cmd window, in the powershell window, in CMDER, in tabby, every commandline i colud find, and as you can see, I use quite some of them.
The Problem is always there: shortcut keys work, but not for "undo" and "redo" ( with "Redo" working with crtl-shift-y)

[maddes8cht]

Screenshot of terminal inside of VSCode:

Screenshot of Windows Terminal:

In both terminals ctrl-z and ctrl-y does not invoke an undo or redo action, while undo and redo does work when called by the menu.

[magiblot]

Okay, thank you very much for your time.

The screenshots don't show anything wrong. What tvdemo displays is the same that Turbo sees internally. So, if the problem was related to the terminal, it would have become evident in the screenshots.

But then I'm out of clues. Turbo does check specifically for Ctrl+Z and Ctrl+Y (and I am unable to reproduce the issue locally).

Just a last idea: the tvdemo.exe I linked earlier is the 32-bit build. Assuming that you usually use the 64-bit version of Turbo, can you also try with the 32-bit turbo.exe?

Also, it calls my attention that Ctrl+Shift+Y triggers Redo (as Ctrl+Y would do). Does Ctrl+Shift+Z (which is also expected to behave like Ctrl+Y) do anything?

Thanks.

[maddes8cht]

Okay :
Seems i got a bit confused by the actual behaviour:

Actually, it looks like ctrl-z and ctrl-y are reversed:
ctrl-z does a redo operation,
ctrl-y does an undo.

It should be reversed, as is

• shown in the menus (where undo is connected with ctrl-z and redo with ctrl-y)
• how it should be according to CUA standard

When i first found the problem, i opened a file, changed something then tried ctrl-z to undo - and nothing happened, because it tried a redo operation instead, but there was nothing to redo.
So when i did an undo via menu, i tried to redo with ctrl-y, but as it executed an undo operation instead, again it looked like "nothing" happened at all.

With a bunch of operations in the queue, you get the picture.
Which also explains why ctrl-shift-y worked.

[maddes8cht]

further information:

In this screenshot, i pressed:

• z
• ctrl-z
• y
• ctrl-y
  As you can see, the z and y presses are recognized correctly, but the ctrl-z and ctrl-y are reversed.
  As I am using a german keyboardlayout, z and y are reversed (QWERTZ Keyboard layout).
  Maybe there is a problem with an incomplete implementation of keyboard layout handling?

[magiblot]

Okay, now that makes sense. Yes, that's exactly the issue. The Turbo Vision library still preserves the original behaviour of detecting key shortcuts by looking at scan codes, which identify the position of the key instead of the associated character. So, in practice, it assumes the keyboard layout is QWERTY. Windows is the only modern platform affected by this issue.

The logical solution could be to stop looking at scan codes. However, at the same time that could be a disadvantage for non-latin keyboard layouts. Related issue: magiblot/tvision#99.