Undo is something that can be misunderstood. Some people expect it should be Undo the last letter I typed; some think Undo last word I typed, Undo the last sentence or Undo parargraph.

However, Undo it means undo everything back to last start point. The start point may be the start of the email if you kept typing and inputting in a ongoing forward manner. But if at any point you perform an edit of a section then a new start point has been effectively created.

If you type some text and then paste some text and then undo - it will undo everything because it is a contiguous input. This is not new, it has been the same for so long I cannot recall it being any different.

Example: If you typed some text such as what gets undone and went to a new line and typed the word test (at this point all the text on both lines is part of the same block using undo now would remove all of it - so do not do it) then used 'back space' to edit thus removing the t so you have tes, this effectly means this is a new starting point as there has been an edit, now retype in the letter t and that becomes the new start point; now use Ctrl+Z to undo, you will find only the letter t gets removed. Use Ctrl+Z again and the t is reinserted as that was the previous edit section, Use 'Ctrl+Z' again and everything is removed as that was all part of the same contiguous editing block.

Note: if you ever type a section and then want to preserve it - add a space and use backspace to clear the space or type a double full stop/period and then use backspace to clear one of full stops. This acts like an edit meaning if you then pasted in text and needed to undo, a Ctrl+Z would only undo back to last new starting point - the edit of the space/full stop so Undo in this case would only remove the pasted section.

This is a neat trick to remember - using the backspace as an edit to reset a start point. This is particulary useful for those who like to use Undo.

That's all well and good but what happens if by accident you used Undo and the whole lot disappears. Do this: 'Edit' > 'Redo' (Ctrl+Y) will get it back. Using 'Ctrl+Y' Redo is used as a reverse of Undo 'Ctrl+Z'

Hello Toad-Hall,

Thank you very much for your detailed answer! I get your point about different expectations about "Undo".

Actually everything would be fine for me, if the 'Redo' would work as you describe, yet in case of normal paste from MS Word it simply does not work in my case - the pasted text with the entire section back to the last edit point will disappear and cannot be restored. The 'Redo' (CTRL+Z), even if activated repeatedly, has no effect anymore. So the solutions you propose unfortunately do not work in this particular case.

Only if I paste text from Word as "paste without formatting", the 'Redo' behaves normally - as you describe it. I checked inserting from browser or email, and it also works normally. Could this be then a Word-related bug?

Best regards,

Yes, it is a word related thing and is about how Microsoft place the information into the clipboard for Thunderbird to fetch.

I have forgotten most of what I learned when I investigated this years ago, but word places many copies of data on the clipboard and essentially Thunderbird picked the wrong one. IIRC correctly it was the word version in HTML that messes up. It was related to CSS and words implementation of it if I recall correctly. But how could you expect a program composing in HTML to select anything but the HTML version as a first choice. The text and RTF versions on the clip board were not an issue, as you have found with the text version.

Thank you very much, Matt! This seems to identify the origin of the problem.

Is there a way to get the lost written text back? If not, are there any chances to adapt the implementation of Word HTML clipboard data in the future versions of Thunderbird?