I have v6.3.3.
One of my favorite features of NotePad++ is multi-line editing: holding SHIFT + ALT and moving the arrow keys to span multiple lines and columns, and then deleting or editing.
Now, since I updated to 6.3.3—and I tried re-updating several times, and removing all plugins—when I do a multi-line select and press TAB, to indent multiple lines, it starts selecting text that I didn't select, and then TAB erases it.
I see inconsistent behavior when using SHIFT-ALT to select and either tabbing or shift-tabbing on both the local and portable packages of Notepad++. For example, shift-tab deleted the first 3 lines I had selected in the local version. Tabbing with 12 lines selected worked the first two times and then started deleting random characters from all lines, also with the local, standard version. Granted, I've never used it before, so I am unsure of how it is supposed to work. What is SHIFT-ALT supposed to do?
To indent or unindent multiple lines, I SHIFT and then move the cursor with the arrow keys or use the mouse and then TAB or SHIFT-TAB to indent and unindent. This works consistently on both the local and portable versions of Notepad++ 6.3.3.
Sometimes, the impossible can become possible, if you're awesome!
SOLVED (for me anyway)
I had Samsung KIES and Samsung USB drivers installed for my Samsung Android phone.
After realizing that KIES is a terrible program, I removed it.
Notepad portable began to work perfectly (as far as multi-line tabs).
I reinstalled the USB drivers for another program to work with my phone, and Notepad's multi-line tabs stopped working.
I uninstalled the drivers, and it worked again.
So, in my case, at least, it appears to have been a conflict between notepad portable and Samsung USB drivers (and possibly the KIES program).
Hope this helps.
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Benjamin J DeLong