Version 4.5.4 (2356)
OS Windows XP Pro

This seemed to just "suddenly" start going wrong so I uninstalled and
reinstalled again and it's still behaving in the wrong way.

I can repeat it with the following steps:

Create a new file and put four lines of text in it.
see http://www.fogcat.co.uk/pspad/step1.png

Move the cursor to the start of line 3 and hit tab. PsPad appears to insert two
tabs, one where you'd expect and one after the first character of the line and
also put a space after the cursor.

http://www.fogcat.co.uk/pspad/step2.png

Hitting tab a couple more times  inserts an extra tab in the middle of the line
and one at the end.

http://www.fogcat.co.uk/pspad/step3.png

>From then on the cursor positioning seems to be thrown off, using backspace
doesn't delete the characters you would expect.

-- 
<http://forum.pspad.com/read.php?4,52380,52380>
PSPad freeware editor http://www.pspad.com

Odpovedet emailem