Incorrect vertical line on cursor position

Hello,
I've noticed minor bug with multi-byte encoded characters. I think that the vertical line position depends on not the character count but the byte count.
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Error Description :
"Show vertical line on cursor position" option with multi-byte encodings shows the vertical line on incorrect position.

Version : 4.6.2(2750)

Platform : Windows 10 Pro(1607), 64-bit edition, Japanese

Instructions to Simulate Error :
1. Run PSPad.
2. Open "Program Settings.." dialog. (Settings->Program Settings..)
3. Check "Show vertical line on cursor position" option in Editor(part 1).
4. Write a multi-byte encoded characters or copy multi-byte encoded characters to PSPad.
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