Make u_GFileIsDir work
Fix file chooser if given a folder path with no trailing backslash
Fix 'Open' command from the menus on Windows. Fixes #1466

The current font is required to determine the last used directory to be shown.
The method used is the only reliable way of getting hold of that last used font.
Free the return value of GFileDirname
Merge pull request #1482 from jtanx/menuopen

Menuopen