Working on more than one task at once, you may run in some problems with your changes. Say, you have changed some files in a changelist, then switched to another changelist and made a massive refactoring. Oops! Some files in the first changelist are touched too. Now, committing any of these changelists without the other may lead to troubles.
Maia introduces a way to avoid such scenarios. You can protect files in inactive changelists. When you’re trying to change them (by direct editing or by applying a refactoring) you will see a dialog indicating the files to be changed:
The dialog gives you a number of options to resolve the conflict. You can shelve the changes you made in an inactive changelist and unshelve them later. You can move the previously changed files into the active changelist so that they would be committed together. If all conflicting files belong to a single changelist, you can switch to it, and the new changes will be added there. Finally, you can just ignore the notification and manage the conflict manually.
This strict protection is not enabled by default. You should go to Project Settings -> Version Control -> Changelist Conflicts and select the Show conflict resolving dialog option.
By default, IntelliJ IDEA warns you if you changed files from an inactive changelist. They are highlighted in the Project View, and have a yellow stripe in the editor.