If you make a change in the properties of a document in Writer, then the program does not consider this change as a proper "change" in the document, and it will not ask you if you want to save the changes to document on closing. For instance, open a document and press "reset" in the general properties page.
A quick check indicates that this seems to be specific to Writer and not Spreadsheet or Presentation.
This bug seems to be a duplicate of 'Bug 32177 - Writer does not perceive addition of custom document properties as a change for saving' [Status: RESOLVED FIXED].
Please, could you check the bug with the current version LibO 3.4.3 release?
That works fine for me (on WinXP 32b) with this build
[LibreOffice 3.4.3 OOO340m1 (Build:302)].
I confirmed that it is indeed resolved using version LibreOffice 3.4.3
OOO340m1 (Build:302) on Win7/32b. I changed the status to resolved.
My apologies for not finding the duplicate and not checking the most recent version (which has had such a rapid release cycle compared to my past experience with OOo)
Thanks for your quick completion confirmation.
FYI: TDF Wiki · BugReport Details
*** This bug has been marked as a duplicate of bug 32177 ***