Firefox 4 plugin MessageBox issue.

See more:

plugin

Firefox

C++11

I used NPAPI to create a plugin that will be added to Firefox 4. The plugin will show two MessageBox continuous. The first one is OK, but the next one will block, user can't click the button on the messagebox, but if you click the firfox frame it will be OK. Also if you open the error console tool of firefox first, then show the messagebox, you click the error console , the messagebox will block too.
Anyone know how to fix it? Or is anyone had this problem too?
Thanks for any suggestion.