I don't think this should keep making you still scratch your bald head, like last I used PC I mistakenly select a text on this environment and all what did lost I had to go and use my undo and everything Popup back as previous. Again, another thing you should do is to keep previewing your post whenever you typed in some words this would help you alot. You should be that used to the entire system how it operates by now.
I fell victim of this particular frustrating event too many times that I actually got acostomed to making use of my notepad before transferring it to the forum especially if it's a bulky post I'm trying to compile. As a designer sometimes you forget you can't actually use the undo button every time lol...
This is common in SMF software as stated by Bitcoingirl.club.
The core editor remains basic, with Ctrl+Z typically only undoing text input, not UI-driven actions like inserting smileys or BBCode tags.
Was the undo (CTRL+Z) option disabled on purpose?
No, It's the default of the forum software.
Or can our script guy (PowerGlove) make some patch
Yes he can but I don't believe is worth the work(could be wrong) .
An extension would be better in my opinion
Well you do have a point however I'm quite curious about it still, because those smileys are actually text inputs or character inputs that eventually displays as smileys when recognized by the forum's SMF system.