Version: (using KDE KDE 3.4.1) Installed from: Debian testing/unstable Packages Test case: (The responses in capitals are the unexpected ones.) 1) Click "New Message" in KMail. [The built-in editor appears.] 2) Type in a message of arbitrary length. Backspace may be used to correct the text. [There is your text.] 3) Select "Remove whitespace" (or whatever it is called in English.) [Whitespace is removed.] 4) Select "Undo". [THE MESSAGE BLANKS.] 5) Select "Redo". [THE MESSAGE REAPPEARS, BUT THE "REMOVE WHITESPACE" OPERATION IS NOT UNDONE.]
The bug is still present in KMail 1.9.1 (KDE 3.5.3).
In kmail 1.10.1 (kde 4.1.66), the Undo puts the message with the additional whitespaces and the redo removes the additional whitespaces (done several times the undo/redo without problems).
I can confirm that this works in kmail 1.10.1, so I'm closing this.