In reference to a bug originally reported against Firefox:
A Mozilla investigator reports that this rendering flaw is also in IE, so it appears to me that the problem would best be addressed by modifying the HTML produced by the MediaWiki software.
The problem can be exhibited by viewing (with Firefox 17):
The work-around hack is to bracket the gallery with <center> and </center> commands.
If the generator recognized gallery's 'align="center"' command and then wrote the equivalent HTML to that generated by bracketing with <center>...</center> the problem would be solved for at least these two browsers, although I do not know what side effects may ensue.
See the above reported Firefox bug for additional information.
- Leonard G.