Description of the Issue

Post integration of PR #9286, I noticed that the SaveAs dialog used when saving a session does not support forward slashing in the pathname. It would be nice if such slashing were allowed.

Steps to Reproduce the Issue

1. File > _Save Session...
2. Attempt to specify a (valid) full path with forward slashes in its name into the SaveAs dialog's File name box:
   
3. Press the Save button and observe the error:
   
4. Change the slashes to backward ones:
   
5. Observe session file saves without error into the destination pathname

Expected Behavior

To be able to use either forward ( / ) or backward ( \ ) slashes in pathnames in the SaveAs (and Open) dialogs.

Actual Behavior

Unable to use forward slashes.

Debug Information

Notepad++ source after this commit: b9f498f