Yes but it would also require that when you've set up a category in an earlier version outside of the current project, that it is properly selected and displayed even though normally it would not be in the list so that this does not cause issues

Besides the point it would require ajax and/or javascript to handle it properly.

Since MantisBT allows an issue to have a category outside of its current project, i opted for a freedom of choice solution where you can actually do just that.

Why do you feel this should be limited to the current project?

I agree that it requires JavaScript/AJAX and the convenience we have in selecting an external category. In fact, I exploit this forgiveness of mantis :)

One issue I noticed is while filtering issues in View Issues. The category drop down in filter form lists only the categories associated with the project selected. So essentially, the issues reported in external categories doesn't get listed in the results. The only way out is to select All for categories/projects.

This is not a high priority issue and we could wait until we have a robust/in-built ajax library in mantis core.

Yeah i think that is best as i do like to use the base core functions over creating my own as it usually means that the plugin has a higher probability of running properly on new versions of MantisBT

Issue postponed

The code in question has had some updates.
It should better fit the issues mentioned.