Deletes too many characters

Just found a bug in PSPad 4.5.9 2525

### Reproduce:
- make a new empty doc
- paste this (one tab between words; my tab is 2 spaces long):

aa bbb cc
aa bbb cc
aa bb cc
aa bbb cc

- select middle column using ALT key including following tab but not "cc"

- delete

### Result:

aa cc
aa cc
aa c
aa cc

### Problem:
In third line it deletes the first "c" which not was selected. Ctrl-Z doesn't bring back this character.