By default, all EmEditor windows will run in one single process, and no more than one process will run on a system whether or not tabs are displayed. It is recommended to leave this option unchecked so EmEditor minimizes the system's memory usage. However, an application error can cause all documents to terminate even though the EmEditor's error handler can try to save unsaved documents when an application error happens. By checking this option, each window will run in an independent process, and an application error on one document will not cause other documents to terminate. If this is checked, tabs will be disabled and cannot be displayed.
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