In the mIRC script editor, if it is still opened after entering the routine that "save" the code ({} button, changing tab, etc), the undo/redo options become unavalaible.
Even though mIRC disables the undo/redo options under the 'Edit' menu when this happens, the standard combinations ctrl+z or ctrl+y should still work but don't, which indicates that it is intentional.
I don't see any reason to prevent that feature in this case and I would like to see this changed.

It's cntrl-z/cntrl shift-z for undo/redo...

1. Open a script in the Script Editor.
2. Alter the file (like add a space at the end of a line).
3. Click the Check Brackets button, or one of the other options that Wims has said.
4. Click Edit, and you will see that the Undo/Redo are disabled. Same goes with CTRL+Z and CTRL+Y.

Also, no such thing as CTRL+SHIFT+Z

See my answer to that kind of post
ctrl+shift+z doesn't exist, you need to think before posting.

LOL what?

CNTRL-SHIFT-Z is the standard keyboard shortcut for redo. Though some Windows programs use CNTRL-Y, most apps use cntrl-shift-z.

I mean here take a look.

http://msdn.microsoft.com/en-us/library/bb787873%28v=vs.85%29.aspx
That exact link is the real documention about rich edit control (remember, the script editor have one and each channel's editboxes are rich edit control too).
I invite you to scroll down until you can see
Now, see your screenshot ? Why don't you do the same with the script editor and realize control + y is just nicely written next to "redo" ?

I think he was replying to your statement that Ctrl-Shift-Z doesn't exist. It does exist. It just depends on the application. MS Word and Wordpad use Ctrl-Y. Notepad uses Ctrl-Shift-Z. SQL Server 2005 uses both. Those are just some examples.

In the end, I believe Ctrl-Y is the most commonly used for Redo among applications **from my experience**, but I have no stats on that. However, both are commonly used and either one is acceptable.

So to the three of you arguing over X doesn't exist or it isn't X, it's Y... both exist and both are valid depending on the application. It just happens that in mIRC, it's Ctrl-Y and not Ctrl-Shift-Z.

Without looking it up, I believe Ctrl-Shift-Z was the original method used. Shift meant to do the opposite. It is the same as Alt-Tab and Alt-Shift-Tab. Over time, I think people wanted an easier shortcut and so Ctrl-Y was created as the new standard. I could be wrong about that, but I believe that's what happened with those.

Really ?
No, not as a standard for that control.

There's nothing to argu about, ctrl+y is the standard shortcut for redo for a rich edit control and that's all, mIRC didn't chose anything.

Note: notepad doesn't even have a 'redo' option

Yes, Notepad does... it just isn't in the menu.

In any case, your original statement was that Ctrl-Shift-Z didn't exist. You didn't specify that you were only talking about richedit controls until afterwards. As I said, but you ignored by taking "It does exist" out of context, It exists in certain applications, but not in others. As I said later, mIRC doesn't use it.

In any case, that has nothing to do with your original post. As to your post, I've seen other apps clear Undo/Redo when you save. I don't know if most do or not since I don't really pay that much attention to undo/redo, but I know that there are others that do clear it. If cleared (the options are grayed out), then the key combinations also will not work. I guess it's just a matter of whether or not Khaled thinks it's better to clear them on Save or not. The idea behind Save is that you know you have it the way you want it and you're not going need to undo anything. Of course, with scripting, you might want to test something and to do that, you have to save. So it's probably better not to clear the undo/redo cache.

Scroll to the bottom of the page you linked to...

Please stop reviving this off-topic discussion. The mIRC built-in script editor uses Ctrl+Y for undo. Nothing else is relevant.

Let's reserve future posts in this thread for discussion related to the original feature suggestion.

This is correct so I was wrong about the shortcut used in mIRC. Like Ramius it's hard to remember which shortcut does what. CNTRL-Z is Undo. We we're all right about that.

I agree with the original post...