#470 Export to PDF locks PDF-file

[Anders]

When using the standard theme in export to pdf, the
pdf file is locked. The file cannot be opened in
acrobat reader, which claims the file is being
locked by another application.

After closing ganttproject, the file can be opened
with acrobat reader.

These problems were experienced on a WinXP machine.

[Dmitry Barashev]

Logged In: YES
user_id=162766

See also:
http://sourceforge.net/tracker/index.php?func=detail&aid=1087066&group_id=72728&atid=535427